update

Reviewed-on: #7

AI_prompt.txt

@@ -12,4 +12,42 @@ Role: Principal Systems Architect & Lead Software Engineer.Objective: Implement
 
 
 
-Create a walkthrough for Julia service-A service sending a mix-content chat message to Julia service-B. the chat message must includes 
+Create a walkthrough for Julia service-A service sending a mix-content chat message to Julia service-B. the chat message must includes 
+
+
+
+
+
+
+I updated the following:
+- NATSBridge.jl. Essentially I add NATS_connection keyword and new publish_message function to support the keyword. 
+
+Use them and ONLY them as ground truth.
+
+Then update the following files accordingly:
+- architecture.md
+- implementation.md
+
+All API should be semantically consistent and naming should be consistent across the board.
+
+
+
+
+
+
+
+
+
+Task: Update NATSBridge.js to reflect recent changes in NATSBridge.jl and docs
+
+Context: NATSBridge.jl and docs has been updated.
+
+Requirements:
+
+Source of Truth: Treat the updated NATSBridge.jl and docs as the definitive source.
+API Consistency: Ensure the Main Package API (e.g., smartsend(), publish_message()) uses consistent naming across all three supported languages.
+Ecosystem Variance: Low-level native functions (e.g., NATS.connect(), JSON.read()) should follow the conventions of the specific language ecosystem and do not require cross-language consistency.
+
+
+
+

Project.toml

@@ -1,6 +1,6 @@
 name = "NATSBridge"
 uuid = "f2724d33-f338-4a57-b9f8-1be882570d10"
-version = "0.4.2"
+version = "0.4.3"
 authors = ["narawat <narawat@gmail.com>"]
 
 [deps]

docs/architecture.md

@@ -17,16 +17,16 @@ The system uses **handler functions** to abstract file server operations, allowi
 
 ```julia
 # Upload handler - uploads data to file server and returns URL
-# The handler is passed to smartsend as fileserverUploadHandler parameter
+# The handler is passed to smartsend as fileserver_upload_handler parameter
 # It receives: (fileserver_url::String, dataname::String, data::Vector{UInt8})
 # Returns: Dict{String, Any} with keys: "status", "uploadid", "fileid", "url"
-fileserverUploadHandler(fileserver_url::String, dataname::String, data::Vector{UInt8})::Dict{String, Any}
+fileserver_upload_handler(fileserver_url::String, dataname::String, data::Vector{UInt8})::Dict{String, Any}
 
 # Download handler - fetches data from file server URL with exponential backoff
-# The handler is passed to smartreceive as fileserverDownloadHandler parameter
+# The handler is passed to smartreceive as fileserver_download_handler parameter
 # It receives: (url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)
 # Returns: Vector{UInt8} (the downloaded data)
-fileserverDownloadHandler(url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)::Vector{UInt8}
+fileserver_download_handler(url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)::Vector{UInt8}
 ```
 
 This design allows the system to support multiple file server backends without changing the core messaging logic.
@@ -40,21 +40,21 @@ The system uses a **standardized list-of-tuples format** for all payload operati
 # Input format for smartsend (always a list of tuples with type info)
 [(dataname1, data1, type1), (dataname2, data2, type2), ...]
 
-# Output format for smartreceive (returns envelope dictionary with payloads field)
+# Output format for smartreceive (returns a dictionary-like object with payloads field containing list of tuples)
-# Returns: Dict with envelope metadata and payloads field containing list of tuples
+# Returns: Dict-like object with envelope metadata and payloads field containing Vector{Tuple{String, Any, String}}
 # {
-#   "correlationId": "...",
+#   "correlation_id": "...",
-#   "msgId": "...",
+#   "msg_id": "...",
 #   "timestamp": "...",
-#   "sendTo": "...",
+#   "send_to": "...",
-#   "msgPurpose": "...",
+#   "msg_purpose": "...",
-#   "senderName": "...",
+#   "sender_name": "...",
-#   "senderId": "...",
+#   "sender_id": "...",
-#   "receiverName": "...",
+#   "receiver_name": "...",
-#   "receiverId": "...",
+#   "receiver_id": "...",
-#   "replyTo": "...",
+#   "reply_to": "...",
-#   "replyToMsgId": "...",
+#   "reply_to_msg_id": "...",
-#   "brokerURL": "...",
+#   "broker_url": "...",
 #   "metadata": {...},
 #   "payloads": [(dataname1, data1, type1), (dataname2, data2, type2), ...]
 # }
@@ -78,17 +78,16 @@ This design allows per-payload type specification, enabling **mixed-content mess
 smartsend(
     "/test",
     [("dataname1", data1, "dictionary")],  # List with one tuple (data, type)
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
-    fileserverUploadHandler=plik_oneshot_upload,
+    fileserver_upload_handler=plik_oneshot_upload
-    metadata=user_provided_envelope_level_metadata
 )
 
 # Multiple payloads in one message with different types
 smartsend(
     "/test",
     [("dataname1", data1, "dictionary"), ("dataname2", data2, "table")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
-    fileserverUploadHandler=plik_oneshot_upload
+    fileserver_upload_handler=plik_oneshot_upload
 )
 
 # Mixed content (e.g., chat with text, image, audio)
@@ -99,13 +98,14 @@ smartsend(
         ("user_image", image_data, "image"),
         ("audio_clip", audio_data, "audio")
     ],
-    nats_url="nats://localhost:4222"
+    broker_url="nats://localhost:4222"
 )
 
 # Receive returns a dictionary envelope with all metadata and deserialized payloads
-envelope = smartreceive(msg, fileserverDownloadHandler, max_retries, base_delay, max_delay)
+env = smartreceive(msg; fileserver_download_handler=_fetch_with_backoff, max_retries=5, base_delay=100, max_delay=5000)
-# envelope["payloads"] = [("dataname1", data1, type1), ("dataname2", data2, type2), ...]
+# env["payloads"] = [("dataname1", data1, type1), ("dataname2", data2, type2), ...]
-# envelope["correlationId"], envelope["msgId"], etc.
+# env["correlation_id"], env["msg_id"], etc.
+# env is a dictionary containing envelope metadata and payloads field
 ```
 
 ## Architecture Diagram
@@ -138,48 +138,48 @@ flowchart TD
 
 ## System Components
 
-### 1. msgEnvelope_v1 - Message Envelope
+### 1. msg_envelope_v1 - Message Envelope
 
-The `msgEnvelope_v1` structure provides a comprehensive message format for bidirectional communication between Julia, JavaScript, and Python/Micropython applications.
+The `msg_envelope_v1` structure provides a comprehensive message format for bidirectional communication between Julia, JavaScript, and Python/Micropython applications.
 
 **Julia Structure:**
 ```julia
-struct msgEnvelope_v1
+struct msg_envelope_v1
-  correlationId::String       # Unique identifier to track messages across systems
+  correlation_id::String       # Unique identifier to track messages across systems
-  msgId::String               # This message id
+  msg_id::String               # This message id
-  timestamp::String           # Message published timestamp
+  timestamp::String            # Message published timestamp
   
-  sendTo::String              # Topic/subject the sender sends to
+  send_to::String              # Topic/subject the sender sends to
-  msgPurpose::String          # Purpose of this message (ACK | NACK | updateStatus | shutdown | ...)
+  msg_purpose::String          # Purpose of this message (ACK | NACK | updateStatus | shutdown | ...)
-  senderName::String          # Sender name (e.g., "agent-wine-web-frontend")
+  sender_name::String          # Sender name (e.g., "agent-wine-web-frontend")
-  senderId::String            # Sender id (uuid4)
+  sender_id::String            # Sender id (uuid4)
-  receiverName::String        # Message receiver name (e.g., "agent-backend")
+  receiver_name::String        # Message receiver name (e.g., "agent-backend")
-  receiverId::String          # Message receiver id (uuid4 or nothing for broadcast)
+  receiver_id::String          # Message receiver id (uuid4 or nothing for broadcast)
-  replyTo::String             # Topic to reply to
+  reply_to::String             # Topic to reply to
-  replyToMsgId::String        # Message id this message is replying to
+  reply_to_msg_id::String      # Message id this message is replying to
-  brokerURL::String           # NATS server address
+  broker_url::String           # NATS server address
   
   metadata::Dict{String, Any}
-  payloads::AbstractArray{msgPayload_v1}  # Multiple payloads stored here
+  payloads::Vector{msg_payload_v1}  # Multiple payloads stored here
 end
 ```
 
 **JSON Schema:**
 ```json
 {
-  "correlationId": "uuid-v4-string",
+  "correlation_id": "uuid-v4-string",
-  "msgId": "uuid-v4-string",
+  "msg_id": "uuid-v4-string",
   "timestamp": "2024-01-15T10:30:00Z",
   
-  "sendTo": "topic/subject",
+  "send_to": "topic/subject",
-  "msgPurpose": "ACK | NACK | updateStatus | shutdown | chat",
+  "msg_purpose": "ACK | NACK | updateStatus | shutdown | chat",
-  "senderName": "agent-wine-web-frontend",
+  "sender_name": "agent-wine-web-frontend",
-  "senderId": "uuid4",
+  "sender_id": "uuid4",
-  "receiverName": "agent-backend",
+  "receiver_name": "agent-backend",
-  "receiverId": "uuid4",
+  "receiver_id": "uuid4",
-  "replyTo": "topic",
+  "reply_to": "topic",
-  "replyToMsgId": "uuid4",
+  "reply_to_msg_id": "uuid4",
-  "brokerURL": "nats://localhost:4222",
+  "broker_url": "nats://localhost:4222",
   
   "metadata": {
 
@@ -189,7 +189,7 @@ end
     {
       "id": "uuid4",
       "dataname": "login_image",
-      "type": "image",
+      "payload_type": "image",
       "transport": "direct",
       "encoding": "base64",
       "size": 15433,
@@ -201,7 +201,7 @@ end
     {
       "id": "uuid4",
       "dataname": "large_data",
-      "type": "table",
+      "payload_type": "table",
       "transport": "link",
       "encoding": "none",
       "size": 524288,
@@ -214,16 +214,16 @@ end
 }
 ```
 
-### 2. msgPayload_v1 - Payload Structure
+### 2. msg_payload_v1 - Payload Structure
 
-The `msgPayload_v1` structure provides flexible payload handling for various data types across all supported platforms.
+The `msg_payload_v1` structure provides flexible payload handling for various data types across all supported platforms.
 
 **Julia Structure:**
 ```julia
-struct msgPayload_v1
+struct msg_payload_v1
   id::String                    # Id of this payload (e.g., "uuid4")
   dataname::String              # Name of this payload (e.g., "login_image")
-  type::String                  # "text | dictionary | table | image | audio | video | binary"
+  payload_type::String          # "text | dictionary | table | image | audio | video | binary"
   transport::String             # "direct | link"
   encoding::String              # "none | json | base64 | arrow-ipc"
   size::Integer                 # Data size in bytes
@@ -369,6 +369,31 @@ graph TD
 
 ## Implementation Details
 
+### API Consistency Across Languages
+
+**High-Level API (Consistent Across All Languages):**
+- `smartsend(subject, data, ...)` - Main publishing function
+- `smartreceive(msg, ...)` - Main receiving function
+- Message envelope structure (`msg_envelope_v1` / `MessageEnvelope`)
+- Payload structure (`msg_payload_v1` / `MessagePayload`)
+- Transport strategy (direct vs link based on size threshold)
+- Supported payload types: text, dictionary, table, image, audio, video, binary
+
+**Low-Level Native Functions (Language-Specific Conventions):**
+- Julia: `NATS.connect()`, `publish_message()`, function overloading
+- JavaScript: `nats.js` client, native async/await patterns
+- Python: `nats-python` client, native async/await patterns
+
+**Connection Reuse Pattern:**
+- **Julia:** Uses `NATS_connection` keyword parameter with function overloading
+- **JavaScript/Python:** Achieved by creating NATS client outside the function and reusing it in custom handlers
+
+**Note on `is_publish`:**
+- `is_publish` is simply a switch to control automatic publishing
+- When `true` (default): Message is published to NATS automatically
+- When `false`: Returns `(env, env_json_str)` without publishing, allowing manual publishing
+- Connection reuse is achieved separately by creating NATS client outside the function
+
 ### Julia Implementation
 
 #### Dependencies
@@ -383,13 +408,47 @@ graph TD
 ```julia
 function smartsend(
   subject::String,
-  data::AbstractArray{Tuple{String, Any, String}};  # No standalone type parameter
+  data::AbstractArray{Tuple{String, Any, String}, 1};  # List of (dataname, data, type) tuples
-  nats_url::String = "nats://localhost:4222",
+  broker_url::String = DEFAULT_BROKER_URL,  # NATS server URL
-  fileserverUploadHandler::Function = plik_oneshot_upload,
+  fileserver_url = DEFAULT_FILESERVER_URL,
-  size_threshold::Int = 1_000_000  # 1MB
+  fileserver_upload_handler::Function = plik_oneshot_upload,
+  size_threshold::Int = DEFAULT_SIZE_THRESHOLD,
+  correlation_id::Union{String, Nothing} = nothing,
+  msg_purpose::String = "chat",
+  sender_name::String = "NATSBridge",
+  receiver_name::String = "",
+  receiver_id::String = "",
+  reply_to::String = "",
+  reply_to_msg_id::String = "",
+  is_publish::Bool = true,   # Whether to automatically publish to NATS
+  NATS_connection::Union{NATS.Connection, Nothing} = nothing  # Pre-existing NATS connection (optional, saves connection overhead)
 )
 ```
 
+**Keyword Parameter - NATS_connection:**
+- `NATS_connection::Union{NATS.Connection, Nothing} = nothing` - Pre-existing NATS connection. When provided, `smartsend` uses this connection instead of creating a new one, avoiding the overhead of connection establishment. This is useful for high-frequency publishing scenarios where connection reuse provides performance benefits.
+
+**Connection Handling Logic:**
+```julia
+if is_publish == false
+  # skip publish a message
+elseif is_publish == true && NATS_connection === nothing
+  publish_message(broker_url, subject, env_json_str, cid)  # Creates new connection
+elseif is_publish == true && NATS_connection !== nothing
+  publish_message(NATS_connection, subject, env_json_str, cid)  # Uses provided connection
+end
+```
+
+**Return Value:**
+- Returns a tuple `(env, env_json_str)` where:
+  - `env::msg_envelope_v1` - The envelope object containing all metadata and payloads
+  - `env_json_str::String` - JSON string representation of the envelope for publishing
+
+**Options:**
+- `is_publish::Bool = true` - When `true` (default), the message is automatically published to NATS. When `false`, the function returns the envelope and JSON string without publishing, allowing manual publishing via NATS request-reply pattern.
+
+The envelope object can be accessed directly for programmatic use, while the JSON string can be published directly to NATS using the request-reply pattern.
+
 **Input Format:**
 - `data::AbstractArray{Tuple{String, Any, String}}` - **Must be a list of (dataname, data, type) tuples**: `[("dataname1", data1, "type1"), ("dataname2", data2, "type2"), ...]`
 - Even for single payloads: `[(dataname1, data1, "type1")]`
@@ -406,8 +465,8 @@ function smartsend(
 
 ```julia
 function smartreceive(
-    msg::NATS.Message,
+    msg::NATS.Msg;
-    fileserverDownloadHandler::Function;
+    fileserver_download_handler::Function = _fetch_with_backoff,
     max_retries::Int = 5,
     base_delay::Int = 100,
     max_delay::Int = 5000
@@ -416,17 +475,17 @@ function smartreceive(
     # Iterate through all payloads
     # For each payload: check transport type
     #   If direct: decode Base64 payload
-    #   If link: fetch from URL with exponential backoff using fileserverDownloadHandler
+    #   If link: fetch from URL with exponential backoff using fileserver_download_handler
     # Deserialize payload based on type
     # Return envelope dictionary with all metadata and deserialized payloads
 end
 ```
 
 **Output Format:**
-- Returns a dictionary (key-value map) containing all envelope fields:
+- Returns a JSON object (dictionary) containing all envelope fields:
-  - `correlationId`, `msgId`, `timestamp`, `sendTo`, `msgPurpose`, `senderName`, `senderId`, `receiverName`, `receiverId`, `replyTo`, `replyToMsgId`, `brokerURL`
+  - `correlation_id`, `msg_id`, `timestamp`, `send_to`, `msg_purpose`, `sender_name`, `sender_id`, `receiver_name`, `receiver_id`, `reply_to`, `reply_to_msg_id`, `broker_url`
   - `metadata` - Message-level metadata dictionary
-  - `payloads` - List of dictionaries, each containing deserialized payload data
+  - `payloads` - List of tuples, each containing `(dataname, data, type)` with deserialized payload data
 
 **Process Flow:**
 1. Parse the JSON envelope to extract all fields
@@ -434,71 +493,253 @@ end
 3. For each payload:
    - Determine transport type (`direct` or `link`)
    - If `direct`: decode Base64 data from the message
-   - If `link`: fetch data from URL using exponential backoff (via `fileserverDownloadHandler`)
+   - If `link`: fetch data from URL using exponential backoff (via `fileserver_download_handler`)
    - Deserialize based on payload type (`dictionary`, `table`, `binary`, etc.)
 4. Return envelope dictionary with `payloads` field containing list of `(dataname, data, type)` tuples
 
-**Note:** The `fileserverDownloadHandler` receives `(url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)` and returns `Vector{UInt8}`.
+**Note:** The `fileserver_download_handler` receives `(url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)` and returns `Vector{UInt8}`.
+
+#### publish_message Function
+
+The `publish_message` function provides two overloads for publishing messages to NATS:
+
+**Overload 1 - URL-based publishing (creates new connection):**
+```julia
+function publish_message(broker_url::String, subject::String, message::String, correlation_id::String)
+  conn = NATS.connect(broker_url)  # Create NATS connection
+  publish_message(conn, subject, message, correlation_id)
+end
+```
+
+**Overload 2 - Connection-based publishing (uses pre-existing connection):**
+```julia
+function publish_message(conn::NATS.Connection, subject::String, message::String, correlation_id::String)
+  try
+    NATS.publish(conn, subject, message)  # Publish message to NATS
+    log_trace(correlation_id, "Message published to $subject")  # Log successful publish
+  finally
+    NATS.drain(conn)  # Ensure connection is closed properly
+  end
+end
+```
+
+**Use Case:** Use the connection-based overload when you already have an established NATS connection and want to publish multiple messages without the overhead of creating a new connection for each publish. This is a Julia-specific optimization that leverages function overloading.
+
+**Integration with smartsend:**
+```julia
+# When NATS_connection is provided to smartsend, it uses the connection-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    NATS_connection=my_connection,  # Pre-existing connection
+    is_publish=true
+)
+# Uses: publish_message(NATS_connection, subject, env_json_str, cid)
+
+# When NATS_connection is not provided, it uses the URL-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    broker_url="nats://localhost:4222",
+    is_publish=true
+)
+# Uses: publish_message(broker_url, subject, env_json_str, cid)
+```
+
+**API Consistency Note:**
+- **High-level API (smartsend, smartreceive):** Uses consistent naming across all three languages (Julia, JavaScript, Python/Micropython)
+- **Low-level native functions (NATS.connect(), publish_message()):** Follow the conventions of the specific language ecosystem and do not require cross-language consistency
 
 ### JavaScript Implementation
 
 #### Dependencies
 - `nats.js` - Core NATS functionality
 - `apache-arrow` - Arrow IPC serialization
-- `uuid` - Correlation ID generation
+- `uuid` - Correlation ID and message ID generation
+- `base64-arraybuffer` - Base64 encoding/decoding
+- `node-fetch` or `fetch` - HTTP client for file server
 
 #### smartsend Function
 
 ```javascript
-async function smartsend(subject, data, options = {})
+async function smartsend(
-    // data format: [(dataname, data, type), ...]
+  subject,
-    // options object should include:
+  data,  // List of (dataname, data, type) tuples: [(dataname1, data1, type1), ...]
-    // - natsUrl: NATS server URL
+  options = {}
-    // - fileserverUrl: base URL of the file server
+)
-    // - sizeThreshold: threshold in bytes for transport selection
-    // - correlationId: optional correlation ID for tracing
 ```
 
+**Options:**
+- `broker_url` (String) - NATS server URL (default: `"nats://localhost:4222"`)
+- `fileserver_url` (String) - Base URL of the file server (default: `"http://localhost:8080"`)
+- `size_threshold` (Number) - Threshold in bytes for transport selection (default: `1048576` = 1MB)
+- `correlation_id` (String) - Optional correlation ID for tracing
+- `msg_purpose` (String) - Purpose of the message (default: `"chat"`)
+- `sender_name` (String) - Sender name (default: `"NATSBridge"`)
+- `receiver_name` (String) - Message receiver name (default: `""`)
+- `receiver_id` (String) - Message receiver ID (default: `""`)
+- `reply_to` (String) - Topic to reply to (default: `""`)
+- `reply_to_msg_id` (String) - Message ID this message is replying to (default: `""`)
+- `is_publish` (Boolean) - Whether to automatically publish the message to NATS (default: `true`)
+- `fileserver_upload_handler` (Function) - Custom upload handler function
+
+**Note:** JavaScript uses `is_publish` option (instead of `NATS_connection` keyword) to control automatic publishing behavior. Connection reuse can be achieved by creating a NATS client outside the function and reusing it in a custom `fileserver_upload_handler` or custom publish implementation.
+
+**Return Value:**
+- Returns a Promise that resolves to an object containing:
+  - `env` - The envelope object containing all metadata and payloads
+  - `env_json_str` - JSON string representation of the envelope for publishing
+
 **Input Format:**
 - `data` - **Must be a list of (dataname, data, type) tuples**: `[(dataname1, data1, "type1"), (dataname2, data2, "type2"), ...]`
 - Even for single payloads: `[(dataname1, data1, "type1")]`
 - Each payload can have a different type, enabling mixed-content messages
+- Supported types: `"text"`, `"dictionary"`, `"table"`, `"image"`, `"audio"`, `"video"`, `"binary"`
 
 **Flow:**
-1. Iterate through the list of (dataname, data, type) tuples
+1. Generate correlation ID and message ID if not provided
-2. For each payload: extract the type from the tuple and serialize accordingly
+2. Iterate through the list of `(dataname, data, type)` tuples
-3. Check payload size
+3. For each payload:
-4. If < threshold: publish directly to NATS
+   - Serialize based on payload type
-5. If >= threshold: upload to HTTP server, publish NATS with URL
+   - Check payload size
+   - If < threshold: Base64 encode and include in envelope
+   - If >= threshold: Upload to HTTP server, store URL in envelope
+4. Publish the JSON envelope to NATS
+5. Return envelope object and JSON string
 
 #### smartreceive Handler
 
 ```javascript
 async function smartreceive(msg, options = {})
-    // options object should include:
-    // - fileserverDownloadHandler: function to fetch data from file server URL
-    // - max_retries: maximum retry attempts for fetching URL
-    // - base_delay: initial delay for exponential backoff in ms
-    // - max_delay: maximum delay for exponential backoff in ms
-    // - correlationId: optional correlation ID for tracing
 ```
 
+**Options:**
+- `fileserver_download_handler` (Function) - Custom download handler function
+- `max_retries` (Number) - Maximum retry attempts for fetching URL (default: `5`)
+- `base_delay` (Number) - Initial delay for exponential backoff in ms (default: `100`)
+- `max_delay` (Number) - Maximum delay for exponential backoff in ms (default: `5000`)
+- `correlation_id` (String) - Optional correlation ID for tracing
+
 **Output Format:**
-- Returns a dictionary (key-value map) containing all envelope fields:
+- Returns a Promise that resolves to an object containing all envelope fields:
-  - `correlationId`, `msgId`, `timestamp`, `sendTo`, `msgPurpose`, `senderName`, `senderId`, `receiverName`, `receiverId`, `replyTo`, `replyToMsgId`, `brokerURL`
+  - `correlation_id`, `msg_id`, `timestamp`, `send_to`, `msg_purpose`, `sender_name`, `sender_id`, `receiver_name`, `receiver_id`, `reply_to`, `reply_to_msg_id`, `broker_url`
   - `metadata` - Message-level metadata dictionary
-  - `payloads` - List of dictionaries, each containing deserialized payload data
+  - `payloads` - List of tuples, each containing `(dataname, data, type)` with deserialized payload data
 
 **Process Flow:**
 1. Parse the JSON envelope to extract all fields
-2. Iterate through each payload in `payloads`
+2. Iterate through each payload in `payloads` array
+3. For each payload:
+    - Determine transport type (`direct` or `link`)
+    - If `direct`: Base64 decode the data from the message
+    - If `link`: Fetch data from URL using exponential backoff (via `fileserver_download_handler`)
+    - Deserialize based on payload type (`dictionary`, `table`, `binary`, etc.)
+4. Return envelope object with `payloads` field containing list of `(dataname, data, type)` tuples
+
+**Note:** The `fileserver_download_handler` receives `(url, max_retries, base_delay, max_delay, correlation_id)` and returns `ArrayBuffer` or `Uint8Array`.
+
+### Python/Micropython Implementation
+
+#### Dependencies
+- `nats-python` - Core NATS functionality
+- `pyarrow` - Arrow IPC serialization
+- `uuid` - Correlation ID and message ID generation
+- `base64` - Base64 encoding/decoding
+- `requests` or `aiohttp` - HTTP client for file server
+
+#### smartsend Function
+
+```python
+def smartsend(
+    subject: str,
+    data: List[Tuple[str, Any, str]],  # List of (dataname, data, type) tuples
+    broker_url: str = DEFAULT_BROKER_URL,
+    fileserver_url: str = DEFAULT_FILESERVER_URL,
+    fileserver_upload_handler: Callable = plik_oneshot_upload,
+    size_threshold: int = DEFAULT_SIZE_THRESHOLD,
+    correlation_id: Union[str, None] = None,
+    msg_purpose: str = "chat",
+    sender_name: str = "NATSBridge",
+    receiver_name: str = "",
+    receiver_id: str = "",
+    reply_to: str = "",
+    reply_to_msg_id: str = "",
+    is_publish: bool = True
+) -> Tuple[MessageEnvelope, str]
+```
+
+**Options:**
+- `broker_url` (str) - NATS server URL (default: `"nats://localhost:4222"`)
+- `fileserver_url` (str) - Base URL of the file server (default: `"http://localhost:8080"`)
+- `size_threshold` (int) - Threshold in bytes for transport selection (default: `1048576` = 1MB)
+- `correlation_id` (str) - Optional correlation ID for tracing (auto-generated if None)
+- `msg_purpose` (str) - Purpose of the message (default: `"chat"`)
+- `sender_name` (str) - Sender name (default: `"NATSBridge"`)
+- `receiver_name` (str) - Message receiver name (default: `""`)
+- `receiver_id` (str) - Message receiver ID (default: `""`)
+- `reply_to` (str) - Topic to reply to (default: `""`)
+- `reply_to_msg_id` (str) - Message ID this message is replying to (default: `""`)
+- `is_publish` (bool) - Whether to automatically publish the message to NATS (default: `True`)
+- `fileserver_upload_handler` (Callable) - Custom upload handler function
+
+**Note:** Python uses `is_publish` parameter (instead of `NATS_connection` keyword) to control automatic publishing behavior. Connection reuse can be achieved by creating a NATS client outside the function and reusing it in a custom `fileserver_upload_handler` or custom publish implementation.
+
+**Return Value:**
+- Returns a tuple `(env, env_json_str)` where:
+  - `env` - The envelope dictionary containing all metadata and payloads
+  - `env_json_str` - JSON string representation of the envelope for publishing
+
+**Input Format:**
+- `data` - **Must be a list of (dataname, data, type) tuples**: `[(dataname1, data1, "type1"), (dataname2, data2, "type2"), ...]`
+- Even for single payloads: `[(dataname1, data1, "type1")]`
+- Each payload can have a different type, enabling mixed-content messages
+- Supported types: `"text"`, `"dictionary"`, `"table"`, `"image"`, `"audio"`, `"video"`, `"binary"`
+
+**Flow:**
+1. Generate correlation ID and message ID if not provided
+2. Iterate through the list of `(dataname, data, type)` tuples
+3. For each payload:
+   - Serialize based on payload type
+   - Check payload size
+   - If < threshold: Base64 encode and include in envelope
+   - If >= threshold: Upload to HTTP server, store URL in envelope
+4. Publish the JSON envelope to NATS
+5. Return envelope dictionary and JSON string
+
+#### smartreceive Handler
+
+```python
+async def smartreceive(
+    msg: NATS.Message,
+    options: Dict = {}
+)
+```
+
+**Options:**
+- `fileserver_download_handler` (Callable) - Custom download handler function
+- `max_retries` (int) - Maximum retry attempts for fetching URL (default: `5`)
+- `base_delay` (int) - Initial delay for exponential backoff in ms (default: `100`)
+- `max_delay` (int) - Maximum delay for exponential backoff in ms (default: `5000`)
+- `correlation_id` (str) - Optional correlation ID for tracing
+
+**Output Format:**
+- Returns a JSON object (dictionary) containing all envelope fields:
+  - `correlation_id`, `msg_id`, `timestamp`, `send_to`, `msg_purpose`, `sender_name`, `sender_id`, `receiver_name`, `receiver_id`, `reply_to`, `reply_to_msg_id`, `broker_url`
+  - `metadata` - Message-level metadata dictionary
+  - `payloads` - List of tuples, each containing `(dataname, data, payload_type)` with deserialized payload data
+
+**Process Flow:**
+1. Parse the JSON envelope to extract all fields
+2. Iterate through each payload in `payloads` list
 3. For each payload:
    - Determine transport type (`direct` or `link`)
-   - If `direct`: decode Base64 data from the message
+   - If `direct`: Base64 decode the data from the message
-   - If `link`: fetch data from URL using exponential backoff
+   - If `link`: Fetch data from URL using exponential backoff (via `fileserver_download_handler`)
    - Deserialize based on payload type (`dictionary`, `table`, `binary`, etc.)
 4. Return envelope dictionary with `payloads` field containing list of `(dataname, data, type)` tuples
 
+**Note:** The `fileserver_download_handler` receives `(url: str, max_retries: int, base_delay: int, max_delay: int, correlation_id: str)` and returns `bytes`.
+
 ## Scenario Implementations
 
 ### Scenario 1: Command & Control (Small Dictionary)
@@ -690,7 +931,7 @@ async function smartreceive(msg, options = {})
 
 **Use Case:** Full-featured chat system supporting rich media. User can send text, small images directly, or upload large files that get uploaded to HTTP server and referenced via URLs. Claim-check pattern ensures reliable delivery tracking for all message components across all platforms.
 
-**Implementation Note:** The `smartreceive` function iterates through all payloads in the envelope and processes each according to its transport type. See the standard API format in Section 1: `msgEnvelope_v1` supports `AbstractArray{msgPayload_v1}` for multiple payloads.
+**Implementation Note:** The `smartreceive` function iterates through all payloads in the envelope and processes each according to its transport type. See the standard API format in Section 1: `msg_envelope_v1` supports `Vector{msg_payload_v1}` for multiple payloads.
 
 ## Performance Considerations
 

docs/implementation.md

@@ -19,49 +19,102 @@ NATSBridge is implemented in three languages, each providing the same API:
 | **JavaScript** | [`src/NATSBridge.js`](../src/NATSBridge.js) | JavaScript implementation for Node.js and browsers |
 | **Python/Micropython** | [`src/nats_bridge.py`](../src/nats_bridge.py) | Python implementation for desktop and microcontrollers |
 
-### Multi-Payload Support
+### File Server Handler Architecture
 
-The implementation uses a **standardized list-of-tuples format** for all payload operations. **Even when sending a single payload, the user must wrap it in a list.**
+The system uses **handler functions** to abstract file server operations, allowing support for different file server implementations (e.g., Plik, AWS S3, custom HTTP server).
+
+**Handler Function Signatures:**
+
+```julia
+# Upload handler - uploads data to file server and returns URL
+# The handler is passed to smartsend as fileserver_upload_handler parameter
+# It receives: (fileserver_url::String, dataname::String, data::Vector{UInt8})
+# Returns: Dict{String, Any} with keys: "status", "uploadid", "fileid", "url"
+fileserver_upload_handler(fileserver_url::String, dataname::String, data::Vector{UInt8})::Dict{String, Any}
+
+# Download handler - fetches data from file server URL with exponential backoff
+# The handler is passed to smartreceive as fileserver_download_handler parameter
+# It receives: (url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)
+# Returns: Vector{UInt8} (the downloaded data)
+fileserver_download_handler(url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)::Vector{UInt8}
+```
+
+This design allows the system to support multiple file server backends without changing the core messaging logic.
+
+### Multi-Payload Support (Standard API)
+
+The system uses a **standardized list-of-tuples format** for all payload operations. **Even when sending a single payload, the user must wrap it in a list.**
 
 **API Standard:**
 ```julia
 # Input format for smartsend (always a list of tuples with type info)
 [(dataname1, data1, type1), (dataname2, data2, type2), ...]
 
-# Output format for smartreceive (returns envelope dictionary with payloads field)
+# Output format for smartreceive (returns a dictionary with payloads field containing list of tuples)
-# Returns: Dict with envelope metadata and payloads field containing list of tuples
+# Returns: Dict with envelope metadata and payloads field containing Vector{Tuple{String, Any, String}}
 # {
-#   "correlationId": "...",
+#   "correlation_id": "...",
-#   "msgId": "...",
+#   "msg_id": "...",
 #   "timestamp": "...",
-#   "sendTo": "...",
+#   "send_to": "...",
-#   "msgPurpose": "...",
+#   "msg_purpose": "...",
-#   "senderName": "...",
+#   "sender_name": "...",
-#   "senderId": "...",
+#   "sender_id": "...",
-#   "receiverName": "...",
+#   "receiver_name": "...",
-#   "receiverId": "...",
+#   "receiver_id": "...",
-#   "replyTo": "...",
+#   "reply_to": "...",
-#   "replyToMsgId": "...",
+#   "reply_to_msg_id": "...",
-#   "brokerURL": "...",
+#   "broker_url": "...",
 #   "metadata": {...},
 #   "payloads": [(dataname1, data1, type1), (dataname2, data2, type2), ...]
 # }
 ```
 
-Where `type` can be: `"text"`, `"dictionary"`, `"table"`, `"image"`, `"audio"`, `"video"`, `"binary"`
+**Supported Types:**
+- `"text"` - Plain text
+- `"dictionary"` - JSON-serializable dictionaries (Dict, NamedTuple)
+- `"table"` - Tabular data (DataFrame, array of structs)
+- `"image"` - Image data (Bitmap, PNG/JPG bytes)
+- `"audio"` - Audio data (WAV, MP3 bytes)
+- `"video"` - Video data (MP4, AVI bytes)
+- `"binary"` - Generic binary data (Vector{UInt8})
+
+This design allows per-payload type specification, enabling **mixed-content messages** where different payloads can use different serialization formats in a single message.
 
 **Examples:**
 ```julia
-# Single payload - still wrapped in a list (type is required as third element)
+# Single payload - still wrapped in a list
-smartsend("/test", [(dataname1, data1, "text")], ...)
+smartsend(
+    "/test",
+    [("dataname1", data1, "dictionary")],  # List with one tuple (data, type)
+    broker_url="nats://localhost:4222",
+    fileserver_upload_handler=plik_oneshot_upload
+)
 
-# Multiple payloads in one message (each payload has its own type)
+# Multiple payloads in one message with different types
-smartsend("/test", [(dataname1, data1, "dictionary"), (dataname2, data2, "table")], ...)
+smartsend(
+    "/test",
+    [("dataname1", data1, "dictionary"), ("dataname2", data2, "table")],
+    broker_url="nats://localhost:4222",
+    fileserver_upload_handler=plik_oneshot_upload
+)
+
+# Mixed content (e.g., chat with text, image, audio)
+smartsend(
+    "/chat",
+    [
+        ("message_text", "Hello!", "text"),
+        ("user_image", image_data, "image"),
+        ("audio_clip", audio_data, "audio")
+    ],
+    broker_url="nats://localhost:4222"
+)
 
 # Receive returns a dictionary envelope with all metadata and deserialized payloads
-envelope = smartreceive(msg, ...)
+env = smartreceive(msg; fileserver_download_handler=_fetch_with_backoff, max_retries=5, base_delay=100, max_delay=5000)
-# envelope["payloads"] = [(dataname1, data1, "text"), (dataname2, data2, "table"), ...]
+# env["payloads"] = [("dataname1", data1, type1), ("dataname2", data2, type2), ...]
-# envelope["correlationId"], envelope["msgId"], etc.
+# env["correlation_id"], env["msg_id"], etc.
+# env is a dictionary containing envelope metadata and payloads field
 ```
 
 ## Cross-Platform Interoperability
@@ -95,24 +148,26 @@ NATSBridge is designed for seamless communication between Julia, JavaScript, and
 ### Example: Julia ↔ Python ↔ JavaScript
 
 ```julia
-# Julia sender
+# Julia sender - smartsend returns (env, env_json_str)
 using NATSBridge
 data = [("message", "Hello from Julia!", "text")]
-smartsend("/cross_platform", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/cross_platform", data, broker_url="nats://localhost:4222")
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
 ```javascript
 // JavaScript receiver
 const { smartreceive } = require('./src/NATSBridge');
-const envelope = await smartreceive(msg);
+const env = await smartreceive(msg);
-// envelope.payloads[0].data === "Hello from Julia!"
+// env.payloads[0].data === "Hello from Julia!"
 ```
 
 ```python
 # Python sender
 from nats_bridge import smartsend
 data = [("response", "Hello from Python!", "text")]
-smartsend("/cross_platform", data, nats_url="nats://localhost:4222")
+smartsend("/cross_platform", data, broker_url="nats://localhost:4222")
 ```
 
 All three platforms can communicate seamlessly using the same NATS subjects and data format.
@@ -146,15 +201,31 @@ All three implementations (Julia, JavaScript, Python/Micropython) follow the sam
       └─────────────────┘                 └─────────────────┘
 ```
 
-## Files
+## smartsend Return Value
+
+The `smartsend` function now returns a tuple containing both the envelope object and the JSON string representation:
+
+```julia
+env, env_json_str = smartsend(...)
+# env::msg_envelope_v1    - The envelope object with all metadata and payloads
+# env_json_str::String    - JSON string for publishing to NATS
+```
+
+**Options:**
+- `is_publish::Bool = true` - When `true` (default), the message is automatically published to NATS. When `false`, the function returns the envelope and JSON string without publishing, allowing manual publishing via NATS request-reply pattern.
+
+This enables two use cases:
+1. **Programmatic envelope access**: Access envelope fields directly via the `env` object
+2. **Direct JSON publishing**: Publish the JSON string directly using NATS request-reply pattern
 
 ### Julia Module: [`src/NATSBridge.jl`](../src/NATSBridge.jl)
 
 The Julia implementation provides:
 
-- **[`MessageEnvelope`](src/NATSBridge.jl)**: Struct for the unified JSON envelope
+- **[`msg_envelope_v1`](src/NATSBridge.jl)**: Struct for the unified JSON envelope
-- **[`SmartSend()`](src/NATSBridge.jl)**: Handles transport selection based on payload size
+- **[`msg_payload_v1`](src/NATSBridge.jl)**: Struct for individual payload representation
-- **[`SmartReceive()`](src/NATSBridge.jl)**: Handles both direct and link transport
+- **[`smartsend()`](src/NATSBridge.jl)**: Handles transport selection based on payload size
+- **[`smartreceive()`](src/NATSBridge.jl)**: Handles both direct and link transport
 
 ### JavaScript Module: [`src/NATSBridge.js`](../src/NATSBridge.js)
 
@@ -245,9 +316,164 @@ julia test/scenario3_julia_to_julia.jl
 node test/scenario3_julia_to_julia.js
 ```
 
+## API Consistency Across Languages
+
+**High-Level API (Consistent Across All Languages):**
+- `smartsend(subject, data, ...)` - Main publishing function
+- `smartreceive(msg, ...)` - Main receiving function
+- Message envelope structure (`msg_envelope_v1` / `MessageEnvelope`)
+- Payload structure (`msg_payload_v1` / `MessagePayload`)
+- Transport strategy (direct vs link based on size threshold)
+- Supported payload types: text, dictionary, table, image, audio, video, binary
+
+**Low-Level Native Functions (Language-Specific Conventions):**
+- Julia: `NATS.connect()`, `publish_message()`, function overloading
+- JavaScript: `nats.js` client, native async/await patterns
+- Python: `nats-python` client, native async/await patterns
+
+**Connection Reuse Pattern - Key Differences:**
+- **Julia:** Uses `NATS_connection` keyword parameter with function overloading for automatic connection management
+- **JavaScript/Python:** Achieved by creating NATS client outside the function and reusing it in custom handlers or custom publish implementations
+
+**Why the Difference?**
+- Julia supports function overloading and keyword arguments, allowing `NATS_connection` to be passed as an optional parameter
+- JavaScript/Python use a simpler `is_publish` option to control automatic publishing
+- `is_publish` is simply a switch: when `true`, publish automatically; when `false`, return `(env, env_json_str)` without publishing
+- For connection reuse in JavaScript/Python, create a NATS client once and reuse it in your custom `fileserver_upload_handler` or custom publish logic
+
 ## Usage
 
-### Scenario 0: Basic Multi-Payload Example
+### Scenario 1: Command & Control (Small Dictionary)
+
+**Focus:** Sending small dictionary configurations across platforms. This is the simplest use case for command and control scenarios.
+
+**Julia (Sender/Receiver):**
+```julia
+using NATSBridge
+
+# Send small dictionary config (wrapped in list with type)
+config = Dict("step_size" => 0.01, "iterations" => 1000, "threshold" => 0.5)
+env, env_json_str = smartsend(
+    "control",
+    [("config", config, "dictionary")],
+    broker_url="nats://localhost:4222"
+)
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
+```
+
+**Julia (Sender/Receiver) with NATS_connection for connection reuse:**
+```julia
+using NATSBridge
+
+# Create connection once for high-frequency publishing
+conn = NATS.connect("nats://localhost:4222")
+
+# Send multiple messages using the same connection (saves connection overhead)
+for i in 1:100
+    config = Dict("iteration" => i, "data" => rand())
+    smartsend(
+        "control",
+        [("config", config, "dictionary")],
+        NATS_connection=conn,  # Reuse connection
+        is_publish=true
+    )
+end
+
+# Close connection when done
+NATS.close(conn)
+```
+
+**Use Case:** High-frequency publishing scenarios where connection reuse provides performance benefits by avoiding the overhead of establishing a new NATS connection for each message.
+
+**JavaScript (Sender/Receiver):**
+```javascript
+const { smartsend } = require('./src/NATSBridge');
+
+// Create small dictionary config
+// Send via smartsend with type="dictionary"
+const config = {
+    step_size: 0.01,
+    iterations: 1000,
+    threshold: 0.5
+};
+
+// Use is_publish option to control automatic publishing
+await smartsend("control", [
+    { dataname: "config", data: config, type: "dictionary" }
+], {
+    is_publish: true  // Automatically publish to NATS
+});
+```
+
+**Connection Reuse in JavaScript:**
+To achieve connection reuse in JavaScript, create a NATS client outside the function and use it in a custom `fileserver_upload_handler` or custom publish implementation:
+
+```javascript
+const { connect } = require('nats');
+const { smartsend } = require('./src/NATSBridge');
+
+// Create connection once
+const nc = await connect({ servers: ['nats://localhost:4222'] });
+
+// Send multiple messages using the same connection
+for (let i = 0; i < 100; i++) {
+    const config = { iteration: i, data: Math.random() };
+    
+    // Option 1: Use is_publish=false and publish manually with your connection
+    const { env, env_json_str } = await smartsend("control", [
+        { dataname: "config", data: config, type: "dictionary" }
+    ], { is_publish: false });
+    
+    // Publish with your existing connection
+    await nc.publish("control", env_json_str);
+}
+
+// Close connection when done
+await nc.close();
+```
+
+**Python/Micropython (Sender/Receiver):**
+```python
+from nats_bridge import smartsend
+
+# Create small dictionary config
+# Send via smartsend with type="dictionary"
+config = {
+    "step_size": 0.01,
+    "iterations": 1000,
+    "threshold": 0.5
+}
+
+# Use is_publish parameter to control automatic publishing
+smartsend("control", [("config", config, "dictionary")], is_publish=True)
+```
+
+**Connection Reuse in Python:**
+To achieve connection reuse in Python, create a NATS client outside the function and use it in a custom `fileserver_upload_handler` or custom publish implementation:
+
+```python
+from nats_bridge import smartsend
+import nats
+
+# Create connection once
+nc = await nats.connect("nats://localhost:4222")
+
+# Send multiple messages using the same connection
+for i in range(100):
+    config = {"iteration": i, "data": random.random()}
+    
+    # Option 1: Use is_publish=False and publish manually with your connection
+    env, env_json_str = smartsend("control", [("config", config, "dictionary")], is_publish=False)
+    
+    # Publish with your existing connection
+    await nc.publish("control", env_json_str)
+
+# Close connection when done
+await nc.close()
+```
+
+### Basic Multi-Payload Example
 
 #### Python/Micropython (Sender)
 ```python
@@ -257,21 +483,21 @@ from nats_bridge import smartsend
 smartsend(
     "/test",
     [("dataname1", data1, "dictionary"), ("dataname2", data2, "table")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     fileserver_url="http://localhost:8080"
 )
 
 # Even single payload must be wrapped in a list with type
-smartsend("/test", [("single_data", mydata, "dictionary")])
+smartsend("/test", [("single_data", mydata, "dictionary")], broker_url="nats://localhost:4222")
 ```
 
 #### Python/Micropython (Receiver)
 ```python
 from nats_bridge import smartreceive
 
-# Receive returns a list of (dataname, data, type) tuples
+# Receive returns a dictionary with envelope metadata and payloads field
-payloads = smartreceive(msg)
+env = smartreceive(msg)
-# payloads = [(dataname1, data1, "dictionary"), (dataname2, data2, "table"), ...]
+# env["payloads"] = [(dataname1, data1, "dictionary"), (dataname2, data2, "table"), ...]
 ```
 
 #### JavaScript (Sender)
@@ -315,18 +541,18 @@ const nc = await connect({ servers: ['nats://localhost:4222'] });
 const sub = nc.subscribe("control");
 
 for await (const msg of sub) {
-    const envelope = await smartreceive(msg);
+    const env = await smartreceive(msg);
     
     // Process the payloads from the envelope
-    for (const payload of envelope.payloads) {
+    for (const payload of env.payloads) {
         const { dataname, data, type } = payload;
         console.log(`Received ${dataname} of type ${type}`);
         console.log(`Data: ${JSON.stringify(data)}`);
     }
     
     // Also access envelope metadata
-    console.log(`Correlation ID: ${envelope.correlationId}`);
+    console.log(`Correlation ID: ${env.correlation_id}`);
-    console.log(`Message ID: ${envelope.msgId}`);
+    console.log(`Message ID: ${env.msg_id}`);
 }
 ```
 
@@ -344,19 +570,136 @@ df = DataFrame(
     category = rand(["A", "B", "C"], 10_000_000)
 )
 
-# Send via SmartSend - wrapped in a list (type is part of each tuple)
+# Send via smartsend - wrapped in list with type
-await SmartSend("analysis_results", [("table_data", df, "table")]);
+# Large payload will use link transport (HTTP fileserver)
+env, env_json_str = smartsend(
+    "analysis_results",
+    [("table_data", df, "table")],
+    broker_url="nats://localhost:4222",
+    fileserver_url="http://localhost:8080"
+)
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
+#### smartsend Function Signature (Julia)
+
+```julia
+function smartsend(
+  subject::String,
+  data::AbstractArray{Tuple{String, Any, String}, 1};  # List of (dataname, data, type) tuples
+  broker_url::String = DEFAULT_BROKER_URL,  # NATS server URL
+  fileserver_url = DEFAULT_FILESERVER_URL,
+  fileserver_upload_handler::Function = plik_oneshot_upload,
+  size_threshold::Int = DEFAULT_SIZE_THRESHOLD,
+  correlation_id::Union{String, Nothing} = nothing,
+  msg_purpose::String = "chat",
+  sender_name::String = "NATSBridge",
+  receiver_name::String = "",
+  receiver_id::String = "",
+  reply_to::String = "",
+  reply_to_msg_id::String = "",
+  is_publish::Bool = true,
+  NATS_connection::Union{NATS.Connection, Nothing} = nothing  # Pre-existing NATS connection (optional)
+)
+```
+
+**New Keyword Parameter:**
+- `NATS_connection::Union{NATS.Connection, Nothing} = nothing` - Pre-existing NATS connection. When provided, `smartsend` uses this connection instead of creating a new one, avoiding the overhead of connection establishment. This is useful for high-frequency publishing scenarios.
+
+**Connection Handling Logic:**
+```julia
+if is_publish == false
+  # skip publish
+elseif is_publish == true && NATS_connection === nothing
+  publish_message(broker_url, subject, env_json_str, cid)  # Creates new connection
+elseif is_publish == true && NATS_connection !== nothing
+  publish_message(NATS_connection, subject, env_json_str, cid)  # Uses provided connection
+end
+```
+
+**Example with pre-existing connection:**
+```julia
+using NATSBridge
+
+# Create connection once
+conn = NATS.connect("nats://localhost:4222")
+
+# Send multiple messages using the same connection
+for i in 1:100
+    data = rand(1000)
+    smartsend(
+        "analysis_results",
+        [("table_data", data, "table")],
+        NATS_connection=conn,  # Reuse connection
+        is_publish=true
+    )
+end
+
+# Close connection when done
+NATS.close(conn)
+```
+
+#### publish_message Function
+
+The `publish_message` function provides two overloads for publishing messages to NATS:
+
+**Overload 1 - URL-based publishing (creates new connection):**
+```julia
+function publish_message(broker_url::String, subject::String, message::String, correlation_id::String)
+  conn = NATS.connect(broker_url)  # Create NATS connection
+  publish_message(conn, subject, message, correlation_id)
+end
+```
+
+**Overload 2 - Connection-based publishing (uses pre-existing connection):**
+```julia
+function publish_message(conn::NATS.Connection, subject::String, message::String, correlation_id::String)
+  try
+    NATS.publish(conn, subject, message)  # Publish message to NATS
+    log_trace(correlation_id, "Message published to $subject")
+  finally
+    NATS.drain(conn)  # Ensure connection is closed properly
+  end
+end
+```
+
+**Use Case:** Use the connection-based overload when you already have an established NATS connection and want to publish multiple messages without the overhead of creating a new connection for each publish.
+
+**Integration with smartsend:**
+```julia
+# When NATS_connection is provided to smartsend, it uses the connection-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    NATS_connection=my_connection,  # Pre-existing connection
+    is_publish=true
+)
+# Uses: publish_message(NATS_connection, subject, env_json_str, cid)
+
+# When NATS_connection is not provided, it uses the URL-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    broker_url="nats://localhost:4222",
+    is_publish=true
+)
+# Uses: publish_message(broker_url, subject, env_json_str, cid)
+```
+
+**API Consistency Note:**
+- **Julia:** Uses `NATS_connection` keyword parameter with function overloading for automatic connection management
+- **JavaScript/Python:** Use `is_publish` option and achieve connection reuse by creating NATS client outside the function and reusing it in custom handlers or custom publish implementations
+
 #### JavaScript (Receiver)
 ```javascript
 const { smartreceive } = require('./src/NATSBridge');
 
-const envelope = await smartreceive(msg);
+const env = await smartreceive(msg);
 
 // Use table data from the payloads field
 // Note: Tables are sent as arrays of objects in JavaScript
-const table = envelope.payloads;
+const table = env.payloads;
 ```
 
 ### Scenario 3: Live Binary Processing
@@ -365,19 +708,12 @@ const table = envelope.payloads;
 ```python
 from nats_bridge import smartsend
 
-# Binary data wrapped in a list
+# Binary data wrapped in list with type
-binary_data = [
-    ("audio_chunk", binary_buffer, "binary")
-]
-
 smartsend(
     "binary_input",
-    binary_data,
+    [("audio_chunk", binary_buffer, "binary")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
-    metadata={
+    metadata={"sample_rate": 44100, "channels": 1}
-        "sample_rate": 44100,
-        "channels": 1
-    }
 )
 ```
 
@@ -406,10 +742,10 @@ from nats_bridge import smartreceive
 
 # Receive binary data
 def process_binary(msg):
-    envelope = smartreceive(msg)
+    env = smartreceive(msg)
     
-    # Process the binary data from envelope.payloads
+    # Process the binary data from env.payloads
-    for dataname, data, type in envelope["payloads"]:
+    for dataname, data, type in env["payloads"]:
         if type == "binary":
             # data is bytes
             print(f"Received binary data: {dataname}, size: {len(data)}")
@@ -422,10 +758,10 @@ const { smartreceive } = require('./src/NATSBridge');
 
 // Receive binary data
 function process_binary(msg) {
-    const envelope = await smartreceive(msg);
+    const env = await smartreceive(msg);
     
-    // Process the binary data from envelope.payloads
+    // Process the binary data from env.payloads
-    for (const payload of envelope.payloads) {
+    for (const payload of env.payloads) {
         if (payload.type === "binary") {
             // data is an ArrayBuffer or Uint8Array
             console.log(`Received binary data: ${payload.dataname}, size: ${payload.data.length}`);
@@ -441,10 +777,14 @@ function process_binary(msg) {
 ```julia
 using NATSBridge
 
-function publish_health_status(nats_url)
+function publish_health_status(broker_url)
-    # Send status wrapped in a list (type is part of each tuple)
+    # Send status wrapped in list with type
     status = Dict("cpu" => rand(), "memory" => rand())
-    smartsend("health", [("status", status, "dictionary")], nats_url=nats_url)
+    env, env_json_str = smartsend(
+        "health",
+        [("status", status, "dictionary")],
+        broker_url=broker_url
+    )
     sleep(5)  # Every 5 seconds
 end
 ```
@@ -466,8 +806,8 @@ const consumer = await js.pullSubscribe("health", {
 
 // Process historical and real-time messages
 for await (const msg of consumer) {
-    const envelope = await smartreceive(msg);
+    const env = await smartreceive(msg);
-    // envelope.payloads contains the list of payloads
+    // env.payloads contains the list of payloads
     // Each payload has: dataname, data, type
     msg.ack();
 }
@@ -484,11 +824,11 @@ import json
 
 # Device configuration handler
 def handle_device_config(msg):
-    envelope = smartreceive(msg)
+    env = smartreceive(msg)
     
     # Process configuration from payloads
-    for dataname, data, type in envelope["payloads"]:
+    for dataname, data, payload_type in env["payloads"]:
-        if type == "dictionary":
+        if payload_type == "dictionary":
             print(f"Received configuration: {data}")
             # Apply configuration to device
             if "wifi_ssid" in data:
@@ -505,8 +845,8 @@ def handle_device_config(msg):
     smartsend(
         "device/response",
         [("config", config, "dictionary")],
-        nats_url="nats://localhost:4222",
+        broker_url="nats://localhost:4222",
-        reply_to=envelope.get("replyTo")
+        reply_to=env.get("reply_to")
     )
 ```
 
@@ -553,12 +893,14 @@ options_df = DataFrame(
 # Check payload size (< 1MB threshold)
 # Publish directly to NATS with Base64-encoded payload
 # Include metadata for dashboard selection context
-smartsend(
+env, env_json_str = smartsend(
     "dashboard.selection",
     [("options_table", options_df, "table")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     metadata=Dict("context" => "user_selection")
 )
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
 **JavaScript (Receiver):**
@@ -566,11 +908,11 @@ smartsend(
 const { smartreceive, smartsend } = require('./src/NATSBridge');
 
 // Receive NATS message with direct transport
-const envelope = await smartreceive(msg);
+const env = await smartreceive(msg);
 
 // Decode Base64 payload (for direct transport)
-// For tables, data is in envelope.payloads
+// For tables, data is in env.payloads
-const table = envelope.payloads;  // Array of objects
+const table = env.payloads;  // Array of objects
 
 // User makes selection
 const selection = uiComponent.getSelectedOption();
@@ -592,7 +934,6 @@ await smartsend("dashboard.response", [
 **Julia (Sender/Receiver):**
 ```julia
 using NATSBridge
-using DataFrames
 
 # Build chat message with mixed payloads:
 # - Text: direct transport (Base64)
@@ -616,13 +957,15 @@ chat_message = [
     ("large_document", large_file_bytes, "binary")  # Large file, link transport
 ]
 
-smartsend(
+env, env_json_str = smartsend(
     "chat.room123",
     chat_message,
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     msg_purpose="chat",
     reply_to="chat.room123.responses"
 )
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
 **JavaScript (Sender/Receiver):**
@@ -667,7 +1010,7 @@ await smartsend("chat.room123", message);
 
 **Use Case:** Full-featured chat system supporting rich media. User can send text, small images directly, or upload large files that get uploaded to HTTP server and referenced via URLs. Claim-check pattern ensures reliable delivery tracking for all message components.
 
-**Implementation Note:** The `smartreceive` function iterates through all payloads in the envelope and processes each according to its transport type. See the standard API format in Section 1: `msgEnvelope_v1` supports `AbstractArray{msgPayload_v1}` for multiple payloads.
+**Implementation Note:** The `smartreceive` function iterates through all payloads in the envelope and processes each according to its transport type. See the standard API format in Section 1: `msg_envelope_v1` supports `Vector{msg_payload_v1}` for multiple payloads.
 
 ## Configuration
 
@@ -683,19 +1026,19 @@ await smartsend("chat.room123", message);
 
 ```json
 {
-  "correlationId": "uuid-v4-string",
+  "correlation_id": "uuid-v4-string",
-  "msgId": "uuid-v4-string",
+  "msg_id": "uuid-v4-string",
   "timestamp": "2024-01-15T10:30:00Z",
   
-  "sendTo": "topic/subject",
+  "send_to": "topic/subject",
-  "msgPurpose": "ACK | NACK | updateStatus | shutdown | chat",
+  "msg_purpose": "ACK | NACK | updateStatus | shutdown | chat",
-  "senderName": "agent-wine-web-frontend",
+  "sender_name": "agent-wine-web-frontend",
-  "senderId": "uuid4",
+  "sender_id": "uuid4",
-  "receiverName": "agent-backend",
+  "receiver_name": "agent-backend",
-  "receiverId": "uuid4",
+  "receiver_id": "uuid4",
-  "replyTo": "topic",
+  "reply_to": "topic",
-  "replyToMsgId": "uuid4",
+  "reply_to_msg_id": "uuid4",
-  "BrokerURL": "nats://localhost:4222",
+  "broker_url": "nats://localhost:4222",
   
   "metadata": {
     "content_type": "application/octet-stream",
@@ -706,7 +1049,7 @@ await smartsend("chat.room123", message);
     {
       "id": "uuid4",
       "dataname": "login_image",
-      "type": "image",
+      "payload_type": "image",
       "transport": "direct",
       "encoding": "base64",
       "size": 15433,

etc.jl

@@ -0,0 +1,9 @@
+Task: Update README.md to reflect recent changes in NATSbridge package.
+
+Context: the package has been updated with the NATS_connection keyword and the publish_message function.
+
+Requirements:
+
+Source of Truth: Treat the updated NATSbridge code as the definitive source. Update README.md to align exactly with these changes.
+API Consistency: Ensure the Main Package API (e.g., smartsend(), publish_message()) uses consistent naming across all three supported languages.
+Ecosystem Variance: Low-level native functions (e.g., NATS.connect(), JSON.read()) should follow the conventions of the specific language ecosystem and do not require cross-language consistency.

examples/tutorial.md

@@ -107,10 +107,15 @@ python3 -m http.server 8080 --directory /tmp/fileserver
 ```python
 from nats_bridge import smartsend
 
-# Send a text message
+# Send a text message (is_publish=True by default)
 data = [("message", "Hello World", "text")]
-env = smartsend("/chat/room1", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222")
 print("Message sent!")
+
+# Or use is_publish=False to get envelope and JSON without publishing
+env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222", is_publish=False)
+# env: MessageEnvelope object
+# env_json_str: JSON string for publishing to NATS
 ```
 
 #### JavaScript
@@ -118,12 +123,19 @@ print("Message sent!")
 ```javascript
 const { smartsend } = require('./src/NATSBridge');
 
-// Send a text message
+// Send a text message (isPublish=true by default)
 await smartsend("/chat/room1", [
     { dataname: "message", data: "Hello World", type: "text" }
-], { natsUrl: "nats://localhost:4222" });
+], { brokerUrl: "nats://localhost:4222" });
 
 console.log("Message sent!");
+
+// Or use isPublish=false to get envelope and JSON without publishing
+const { env, env_json_str } = await smartsend("/chat/room1", [
+    { dataname: "message", data: "Hello World", type: "text" }
+], { brokerUrl: "nats://localhost:4222", isPublish: false });
+// env: MessageEnvelope object
+// env_json_str: JSON string for publishing to NATS
 ```
 
 #### Julia
@@ -133,7 +145,9 @@ using NATSBridge
 
 # Send a text message
 data = [("message", "Hello World", "text")]
-env = smartsend("/chat/room1", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222")
+# env: msg_envelope_v1 object with all metadata and payloads
+# env_json_str: JSON string representation of the envelope for publishing
 println("Message sent!")
 ```
 
@@ -145,8 +159,8 @@ println("Message sent!")
 from nats_bridge import smartreceive
 
 # Receive and process message
-envelope = smartreceive(msg)
+env = smartreceive(msg)
-for dataname, data, type in envelope["payloads"]:
+for dataname, data, type in env["payloads"]:
     print(f"Received {dataname}: {data}")
 ```
 
@@ -156,8 +170,8 @@ for dataname, data, type in envelope["payloads"]:
 const { smartreceive } = require('./src/NATSBridge');
 
 // Receive and process message
-const envelope = await smartreceive(msg);
+const env = await smartreceive(msg);
-for (const payload of envelope.payloads) {
+for (const payload of env.payloads) {
     console.log(`Received ${payload.dataname}: ${payload.data}`);
 }
 ```
@@ -168,8 +182,8 @@ for (const payload of envelope.payloads) {
 using NATSBridge
 
 # Receive and process message
-envelope = smartreceive(msg, fileserverDownloadHandler)
+env = smartreceive(msg; fileserver_download_handler=_fetch_with_backoff)
-for (dataname, data, type) in envelope["payloads"]
+for (dataname, data, type) in env["payloads"]
     println("Received $dataname: $data")
 end
 ```
@@ -194,7 +208,7 @@ config = {
 
 # Send as dictionary type
 data = [("config", config, "dictionary")]
-env = smartsend("/device/config", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/device/config", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript
@@ -208,9 +222,9 @@ const config = {
     update_interval: 60
 };
 
-await smartsend("/device/config", [
+const { env, env_json_str } = await smartsend("/device/config", [
     { dataname: "config", data: config, type: "dictionary" }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Julia
@@ -225,7 +239,7 @@ config = Dict(
 )
 
 data = [("config", config, "dictionary")]
-smartsend("/device/config", data)
+env, env_json_str = smartsend("/device/config", data, broker_url="nats://localhost:4222")
 ```
 
 ### Example 2: Sending Binary Data (Image)
@@ -241,7 +255,7 @@ with open("image.png", "rb") as f:
 
 # Send as binary type
 data = [("user_image", image_data, "binary")]
-env = smartsend("/chat/image", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/image", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript
@@ -253,9 +267,9 @@ const { smartsend } = require('./src/NATSBridge');
 const fs = require('fs');
 const image_data = fs.readFileSync('image.png');
 
-await smartsend("/chat/image", [
+const { env, env_json_str } = await smartsend("/chat/image", [
     { dataname: "user_image", data: image_data, type: "binary" }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Julia
@@ -267,7 +281,7 @@ using NATSBridge
 image_data = read("image.png")
 
 data = [("user_image", image_data, "binary")]
-smartsend("/chat/image", data)
+env, env_json_str = smartsend("/chat/image", data, broker_url="nats://localhost:4222")
 ```
 
 ### Example 3: Request-Response Pattern
@@ -279,13 +293,15 @@ from nats_bridge import smartsend
 
 # Send command with reply-to
 data = [("command", {"action": "read_sensor"}, "dictionary")]
-env = smartsend(
+env, env_json_str = smartsend(
     "/device/command",
     data,
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     reply_to="/device/response",
     reply_to_msg_id="cmd-001"
 )
+# env: MessageEnvelope object
+# env_json_str: JSON string for publishing to NATS
 ```
 
 #### JavaScript (Responder)
@@ -297,10 +313,10 @@ const { smartreceive, smartsend } = require('./src/NATSBridge');
 const sub = nc.subscribe("/device/command");
 
 for await (const msg of sub) {
-    const envelope = await smartreceive(msg);
+    const env = await smartreceive(msg);
     
     // Process command
-    for (const payload of envelope.payloads) {
+    for (const payload of env.payloads) {
         if (payload.dataname === "command") {
             const command = payload.data;
             
@@ -315,8 +331,8 @@ for await (const msg of sub) {
                 await smartsend("/device/response", [
                     { dataname: "sensor_data", data: response, type: "dictionary" }
                 ], {
-                    reply_to: envelope.replyTo,
+                    reply_to: env.replyTo,
-                    reply_to_msg_id: envelope.msgId
+                    reply_to_msg_id: env.msgId
                 });
             }
         }
@@ -342,10 +358,10 @@ import os
 large_data = os.urandom(2_000_000)  # 2MB of random data
 
 # Send with file server URL
-env = smartsend(
+env, env_json_str = smartsend(
     "/data/large",
     [("large_file", large_data, "binary")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     fileserver_url="http://localhost:8080",
     size_threshold=1_000_000
 )
@@ -364,9 +380,10 @@ const largeData = new ArrayBuffer(2_000_000);
 const view = new Uint8Array(largeData);
 view.fill(42);  // Fill with some data
 
-await smartsend("/data/large", [
+const { env, env_json_str } = await smartsend("/data/large", [
     { dataname: "large_file", data: largeData, type: "binary" }
 ], {
+    brokerUrl: "nats://localhost:4222",
     fileserverUrl: "http://localhost:8080",
     sizeThreshold: 1_000_000
 });
@@ -380,9 +397,10 @@ using NATSBridge
 # Create large data (> 1MB)
 large_data = rand(UInt8, 2_000_000)
 
-env = smartsend(
+env, env_json_str = smartsend(
     "/data/large",
     [("large_file", large_data, "binary")],
+    broker_url="nats://localhost:4222",
     fileserver_url="http://localhost:8080"
 )
 
@@ -409,7 +427,7 @@ data = [
     ("user_avatar", image_data, "image")
 ]
 
-env = smartsend("/chat/mixed", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/mixed", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript
@@ -419,7 +437,7 @@ const { smartsend } = require('./src/NATSBridge');
 
 const fs = require('fs');
 
-await smartsend("/chat/mixed", [
+const { env, env_json_str } = await smartsend("/chat/mixed", [
     {
         dataname: "message_text",
         data: "Hello with image!",
@@ -430,7 +448,7 @@ await smartsend("/chat/mixed", [
         data: fs.readFileSync("avatar.png"),
         type: "image"
     }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Julia
@@ -445,7 +463,7 @@ data = [
     ("user_avatar", image_data, "image")
 ]
 
-smartsend("/chat/mixed", data)
+env, env_json_str = smartsend("/chat/mixed", data, broker_url="nats://localhost:4222")
 ```
 
 ### Example 6: Table Data (Arrow IPC)
@@ -467,7 +485,7 @@ df = pd.DataFrame({
 
 # Send as table type
 data = [("students", df, "table")]
-env = smartsend("/data/students", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/data/students", data, broker_url="nats://localhost:4222")
 ```
 
 #### Julia
@@ -484,7 +502,7 @@ df = DataFrame(
 )
 
 data = [("students", df, "table")]
-smartsend("/data/students", data)
+env, env_json_str = smartsend("/data/students", data, broker_url="nats://localhost:4222")
 ```
 
 ---
@@ -503,7 +521,7 @@ using NATSBridge
 # Send dictionary from Julia to JavaScript
 config = Dict("step_size" => 0.01, "iterations" => 1000)
 data = [("config", config, "dictionary")]
-smartsend("/analysis/config", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/analysis/config", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript Receiver
@@ -512,8 +530,8 @@ smartsend("/analysis/config", data, nats_url="nats://localhost:4222")
 const { smartreceive } = require('./src/NATSBridge');
 
 // Receive dictionary from Julia
-const envelope = await smartreceive(msg);
+const env = await smartreceive(msg);
-for (const payload of envelope.payloads) {
+for (const payload of env.payloads) {
     if (payload.type === "dictionary") {
         console.log("Received config:", payload.data);
         // payload.data = { step_size: 0.01, iterations: 1000 }
@@ -528,9 +546,9 @@ for (const payload of envelope.payloads) {
 ```javascript
 const { smartsend } = require('./src/NATSBridge');
 
-await smartsend("/data/transfer", [
+const { env, env_json_str } = await smartsend("/data/transfer", [
     { dataname: "message", data: "Hello from JS!", type: "text" }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Python Receiver
@@ -538,8 +556,8 @@ await smartsend("/data/transfer", [
 ```python
 from nats_bridge import smartreceive
 
-envelope = smartreceive(msg)
+env = smartreceive(msg)
-for dataname, data, type in envelope["payloads"]:
+for dataname, data, type in env["payloads"]:
     if type == "text":
         print(f"Received from JS: {data}")
 ```
@@ -552,7 +570,7 @@ for dataname, data, type in envelope["payloads"]:
 from nats_bridge import smartsend
 
 data = [("message", "Hello from Python!", "text")]
-smartsend("/chat/python", data)
+env, env_json_str = smartsend("/chat/python", data, broker_url="nats://localhost:4222")
 ```
 
 #### Julia Receiver
@@ -560,8 +578,8 @@ smartsend("/chat/python", data)
 ```julia
 using NATSBridge
 
-envelope = smartreceive(msg, fileserverDownloadHandler)
+env = smartreceive(msg; fileserver_download_handler=_fetch_with_backoff)
-for (dataname, data, type) in envelope["payloads"]
+for (dataname, data, type) in env["payloads"]
     if type == "text"
         println("Received from Python: $data")
     end

examples/walkthrough.md

@@ -132,10 +132,11 @@ class ChatUI {
             });
         }
         
-        await smartsend(
+        const { env, env_json_str } = await smartsend(
             `/chat/${this.currentRoom}`,
             data,
             {
+                brokerUrl: window.config.broker_url,
                 fileserverUrl: window.config.fileserver_url,
                 sizeThreshold: window.config.size_threshold
             }
@@ -216,15 +217,15 @@ class ChatHandler {
     }
     
     async handleMessage(msg) {
-        const envelope = await smartreceive(msg, {
+        const env = await smartreceive(msg, {
             fileserverDownloadHandler: this.downloadFile.bind(this)
         });
         
         // Extract sender info from envelope
-        const sender = envelope.senderName || 'Anonymous';
+        const sender = env.senderName || 'Anonymous';
         
         // Process each payload
-        for (const payload of envelope.payloads) {
+        for (const payload of env.payloads) {
             if (payload.type === 'text') {
                 this.ui.addMessage(sender, payload.data);
             } else if (payload.type === 'image') {
@@ -288,8 +289,8 @@ Let's build a file transfer system that handles large files efficiently.
 const { smartsend } = require('./NATSBridge');
 
 class FileUploadService {
-    constructor(natsUrl, fileserverUrl) {
+    constructor(brokerUrl, fileserverUrl) {
-        this.natsUrl = natsUrl;
+        this.brokerUrl = brokerUrl;
         this.fileserverUrl = fileserverUrl;
     }
     
@@ -304,17 +305,17 @@ class FileUploadService {
             type: 'binary'
         }];
         
-        const envelope = await smartsend(
+        const { env, env_json_str } = await smartsend(
             `/files/${recipient}`,
             data,
             {
-                natsUrl: this.natsUrl,
+                brokerUrl: this.brokerUrl,
                 fileserverUrl: this.fileserverUrl,
                 sizeThreshold: 1048576
             }
         );
         
-        return envelope;
+        return env;
     }
     
     async uploadLargeFile(filePath, recipient) {
@@ -356,12 +357,12 @@ class FileDownloadService {
     
     async downloadFile(sender, downloadId) {
         // Subscribe to sender's file channel
-        const envelope = await smartreceive(msg, {
+        const env = await smartreceive(msg, {
             fileserverDownloadHandler: this.fetchFromUrl.bind(this)
         });
         
         // Process each payload
-        for (const payload of envelope.payloads) {
+        for (const payload of env.payloads) {
             if (payload.type === 'binary') {
                 const filePath = `/downloads/${payload.dataname}`;
                 fs.writeFileSync(filePath, payload.data);
@@ -419,12 +420,12 @@ async function uploadFile(config) {
     const filePath = await rl.question('Enter file path: ');
     const recipient = await rl.question('Enter recipient: ');
     
-    const fileService = new FileUploadService(config.nats_url, config.fileserver_url);
+    const fileService = new FileUploadService(config.broker_url, config.fileserver_url);
     
     try {
-        const envelope = await fileService.uploadFile(filePath, recipient);
+        const env = await fileService.uploadFile(filePath, recipient);
         console.log('Upload successful!');
-        console.log(`File ID: ${envelope.payloads[0].id}`);
+        console.log(`File ID: ${env.payloads[0].id}`);
     } catch (error) {
         console.error('Upload failed:', error.message);
     }
@@ -500,8 +501,8 @@ import time
 import random
 
 class SensorSender:
-    def __init__(self, nats_url: str, fileserver_url: str):
+    def __init__(self, broker_url: str, fileserver_url: str):
-        self.nats_url = nats_url
+        self.broker_url = broker_url
         self.fileserver_url = fileserver_url
         
     def send_reading(self, sensor_id: str, value: float, unit: str):
@@ -514,13 +515,39 @@ class SensorSender:
         
         data = [("reading", reading.to_dict(), "dictionary")]
         
+        # Default: is_publish=True (automatically publishes to NATS)
         smartsend(
             f"/sensors/{sensor_id}",
             data,
-            nats_url=self.nats_url,
+            broker_url=self.broker_url,
             fileserver_url=self.fileserver_url
         )
         
+    def prepare_message_only(self, sensor_id: str, value: float, unit: str):
+        """Prepare a message without publishing (is_publish=False)."""
+        reading = SensorReading(
+            sensor_id=sensor_id,
+            timestamp=datetime.now().isoformat(),
+            value=value,
+            unit=unit
+        )
+        
+        data = [("reading", reading.to_dict(), "dictionary")]
+        
+        # With is_publish=False, returns (env, env_json_str) without publishing
+        env, env_json_str = smartsend(
+            f"/sensors/{sensor_id}/prepare",
+            data,
+            broker_url=self.broker_url,
+            fileserver_url=self.fileserver_url,
+            is_publish=False
+        )
+        
+        # Now you can publish manually using NATS request-reply pattern
+        # nc.request(subject, env_json_str, reply_to=reply_to_topic)
+        
+        return env, env_json_str
+        
     def send_batch(self, readings: List[SensorReading]):
         batch = SensorBatch()
         for reading in readings:
@@ -546,7 +573,7 @@ class SensorSender:
             smartsend(
                 f"/sensors/batch",
                 data,
-                nats_url=self.nats_url,
+                broker_url=self.broker_url,
                 fileserver_url=self.fileserver_url
             )
         else:
@@ -571,9 +598,9 @@ class SensorReceiver:
         self.fileserver_download_handler = fileserver_download_handler
         
     def process_reading(self, msg):
-        envelope = smartreceive(msg, self.fileserver_download_handler)
+        env = smartreceive(msg, self.fileserver_download_handler)
         
-        for dataname, data, data_type in envelope["payloads"]:
+        for dataname, data, data_type in env["payloads"]:
             if data_type == "dictionary":
                 reading = SensorReading(
                     sensor_id=data["sensor_id"],
@@ -605,17 +632,17 @@ Let's build an IoT device using Micropython that connects to NATS.
 import json
 
 class DeviceConfig:
-    def __init__(self, ssid, password, nats_url, device_id):
+    def __init__(self, ssid, password, broker_url, device_id):
         self.ssid = ssid
         self.password = password
-        self.nats_url = nats_url
+        self.broker_url = broker_url
         self.device_id = device_id
         
     def to_dict(self):
         return {
             "ssid": self.ssid,
             "password": self.password,
-            "nats_url": self.nats_url,
+            "broker_url": self.broker_url,
             "device_id": self.device_id
         }
 ```
@@ -630,7 +657,7 @@ import json
 class DeviceBridge:
     def __init__(self, config):
         self.config = config
-        self.nats_url = config.nats_url
+        self.broker_url = config.broker_url
         
     def connect(self):
         # Connect to WiFi
@@ -650,7 +677,7 @@ class DeviceBridge:
         smartsend(
             f"/devices/{self.config.device_id}/status",
             data,
-            nats_url=self.nats_url
+            broker_url=self.broker_url
         )
         
     def send_sensor_data(self, sensor_id, value, unit):
@@ -661,7 +688,7 @@ class DeviceBridge:
         smartsend(
             f"/devices/{self.config.device_id}/sensors/{sensor_id}",
             data,
-            nats_url=self.nats_url
+            broker_url=self.broker_url
         )
         
     def receive_commands(self, callback):
@@ -673,10 +700,10 @@ class DeviceBridge:
             # Poll for messages
             msg = self._poll_for_message()
             if msg:
-                envelope = smartreceive(msg)
+                env = smartreceive(msg)
                 
                 # Process payloads
-                for dataname, data, data_type in envelope["payloads"]:
+                for dataname, data, data_type in env["payloads"]:
                     if dataname == "command":
                         callback(data)
                         
@@ -699,7 +726,7 @@ import random
 config = DeviceConfig(
     ssid="MyNetwork",
     password="password123",
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     device_id="device-001"
 )
 
@@ -748,8 +775,8 @@ import pyarrow as pa
 import io
 
 class DashboardServer:
-    def __init__(self, nats_url, fileserver_url):
+    def __init__(self, broker_url, fileserver_url):
-        self.nats_url = nats_url
+        self.broker_url = broker_url
         self.fileserver_url = fileserver_url
         
     def broadcast_data(self, df):
@@ -766,15 +793,15 @@ class DashboardServer:
         smartsend(
             "/dashboard/data",
             data,
-            nats_url=self.nats_url,
+            broker_url=self.broker_url,
             fileserver_url=self.fileserver_url
         )
         
     def receive_selection(self, callback):
         def handler(msg):
-            envelope = smartreceive(msg)
+            env = smartreceive(msg)
             
-            for dataname, data, data_type in envelope["payloads"]:
+            for dataname, data, data_type in env["payloads"]:
                 if data_type == "dictionary":
                     callback(data)
                     
@@ -807,21 +834,22 @@ class DashboardUI {
     
     async refreshData() {
         // Request fresh data
-        await smartsend("/dashboard/request", [
+        const { env, env_json_str } = await smartsend("/dashboard/request", [
             { dataname: "request", data: { type: "refresh" }, type: "dictionary" }
         ], {
+            brokerUrl: window.config.broker_url,
             fileserverUrl: window.config.fileserver_url
         });
     }
     
     async fetchData() {
         // Subscribe to data updates
-        const envelope = await smartreceive(msg, {
+        const env = await smartreceive(msg, {
             fileserverDownloadHandler: this.fetchFromUrl.bind(this)
         });
         
         // Process table data
-        for (const payload of envelope.payloads) {
+        for (const payload of env.payloads) {
             if (payload.type === 'table') {
                 // Deserialize Arrow IPC
                 this.data = this.deserializeArrow(payload.data);
@@ -928,7 +956,7 @@ def send_batch_readings(self, readings):
     smartsend(
         "/sensors/batch",
         [("batch", arrow_data, "table")],
-        nats_url=self.nats_url
+        broker_url=self.broker_url
     )
 ```
 

plik_fileserver/docker-compose.yml

@@ -0,0 +1,14 @@
+services:
+  plik:
+    image: rootgg/plik:latest
+    container_name: plik-server
+    restart: unless-stopped
+    ports:
+      - "8080:8080"
+    volumes:
+      # # Mount the config file (created below)
+      # - ./plikd.cfg:/home/plik/server/plikd.cfg
+      # Mount local folder for uploads and database
+      - ./plik-data:/data
+    # Set user to match your host UID to avoid permission issues
+    user: "1000:1000"

src/NATSBridge.js

@@ -9,16 +9,16 @@
  * File Server Handler Architecture:
  * The system uses handler functions to abstract file server operations, allowing support
  * for different file server implementations (e.g., Plik, AWS S3, custom HTTP server).
- * 
+ *
  * Handler Function Signatures:
- * 
+ *
  * ```javascript
  * // Upload handler - uploads data to file server and returns URL
  * // The handler is passed to smartsend as fileserverUploadHandler parameter
  * // It receives: (fileserver_url, dataname, data)
  * // Returns: { status, uploadid, fileid, url }
- * async function fileserverUploadHandler(fileserver_url, dataname, data) { ... }
+ * async function plik_oneshot_upload(fileserver_url, dataname, data) { ... }
- * 
+ *
  * // Download handler - fetches data from file server URL with exponential backoff
  * // The handler is passed to smartreceive as fileserverDownloadHandler parameter
  * // It receives: (url, max_retries, base_delay, max_delay, correlation_id)
@@ -98,6 +98,26 @@ function base64ToArrayBuffer(base64) {
     return bytes.buffer;
 }
 
+// Helper: Convert Uint8Array to Base64 string
+function uint8ArrayToBase64(uint8array) {
+    let binary = '';
+    for (let i = 0; i < uint8array.byteLength; i++) {
+        binary += String.fromCharCode(uint8array[i]);
+    }
+    return btoa(binary);
+}
+
+// Helper: Convert Base64 string to Uint8Array
+function base64ToUint8Array(base64) {
+    const binaryString = atob(base64);
+    const len = binaryString.length;
+    const bytes = new Uint8Array(len);
+    for (let i = 0; i < len; i++) {
+        bytes[i] = binaryString.charCodeAt(i);
+    }
+    return bytes;
+}
+
 // Helper: Serialize data based on type
 function _serialize_data(data, type) {
     /**
@@ -114,39 +134,39 @@ function _serialize_data(data, type) {
      */
     if (type === "text") {
         if (typeof data === 'string') {
-            return new TextEncoder().encode(data).buffer;
+            return new TextEncoder().encode(data);
         } else {
             throw new Error("Text data must be a String");
         }
     } else if (type === "dictionary") {
         // JSON data - serialize directly
         const jsonStr = JSON.stringify(data);
-        return new TextEncoder().encode(jsonStr).buffer;
+        return new TextEncoder().encode(jsonStr);
     } else if (type === "table") {
         // Table data - convert to Arrow IPC stream (NOT IMPLEMENTED in pure JavaScript)
         // This would require the apache-arrow library
         throw new Error("Table serialization requires apache-arrow library");
     } else if (type === "image") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Image data must be ArrayBuffer or Uint8Array");
         }
     } else if (type === "audio") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Audio data must be ArrayBuffer or Uint8Array");
         }
     } else if (type === "video") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Video data must be ArrayBuffer or Uint8Array");
         }
     } else if (type === "binary") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Binary data must be ArrayBuffer or Uint8Array");
         }
@@ -171,10 +191,10 @@ function _deserialize_data(data, type, correlation_id) {
      */
     if (type === "text") {
         const decoder = new TextDecoder();
-        return decoder.decode(new Uint8Array(data));
+        return decoder.decode(data);
     } else if (type === "dictionary") {
         const decoder = new TextDecoder();
-        const jsonStr = decoder.decode(new Uint8Array(data));
+        const jsonStr = decoder.decode(data);
         return JSON.parse(jsonStr);
     } else if (type === "table") {
         // Table data - deserialize Arrow IPC stream (NOT IMPLEMENTED in pure JavaScript)
@@ -193,73 +213,16 @@ function _deserialize_data(data, type, correlation_id) {
 }
 
 // Helper: Upload data to file server
+// Internal wrapper that adds correlation_id logging for smartsend
 async function _upload_to_fileserver(fileserver_url, dataname, data, correlation_id) {
     /**
-     * Upload data to HTTP file server (plik-like API)
+     * Internal upload helper - wraps plik_oneshot_upload to add correlation_id logging
-     * 
+     * This allows smartsend to pass correlation_id for tracing without changing the handler signature
-     * This function implements the plik one-shot upload mode:
-     * 1. Creates a one-shot upload session by sending POST request with {"OneShot": true}
-     * 2. Uploads the file data as multipart form data
-     * 3. Returns identifiers and download URL for the uploaded file
      */
     log_trace(correlation_id, `Uploading ${dataname} to fileserver: ${fileserver_url}`);
-    
+    const result = await plik_oneshot_upload(fileserver_url, dataname, data);
-    // Step 1: Get upload ID and token
+    log_trace(correlation_id, `Uploaded to URL: ${result.url}`);
-    const url_getUploadID = `${fileserver_url}/upload`;
+    return result;
-    const headers = {
-        "Content-Type": "application/json"
-    };
-    const body = JSON.stringify({ OneShot: true });
-    
-    let response = await fetch(url_getUploadID, {
-        method: "POST",
-        headers: headers,
-        body: body
-    });
-    
-    if (!response.ok) {
-        throw new Error(`Failed to get upload ID: ${response.status} ${response.statusText}`);
-    }
-    
-    const responseJson = await response.json();
-    const uploadid = responseJson.id;
-    const uploadtoken = responseJson.uploadToken;
-    
-    // Step 2: Upload file data
-    const url_upload = `${fileserver_url}/file/${uploadid}`;
-    
-    // Create multipart form data
-    const formData = new FormData();
-    // Create a Blob from the ArrayBuffer
-    const blob = new Blob([data], { type: "application/octet-stream" });
-    formData.append("file", blob, dataname);
-    
-    response = await fetch(url_upload, {
-        method: "POST",
-        headers: {
-            "X-UploadToken": uploadtoken
-        },
-        body: formData
-    });
-    
-    if (!response.ok) {
-        throw new Error(`Failed to upload file: ${response.status} ${response.statusText}`);
-    }
-    
-    const fileResponseJson = await response.json();
-    const fileid = fileResponseJson.id;
-    
-    // Build the download URL
-    const url = `${fileserver_url}/file/${uploadid}/${fileid}/${encodeURIComponent(dataname)}`;
-    
-    log_trace(correlation_id, `Uploaded to URL: ${url}`);
-    
-    return {
-        status: response.status,
-        uploadid: uploadid,
-        fileid: fileid,
-        url: url
-    };
 }
 
 // Helper: Fetch data from URL with exponential backoff
@@ -276,7 +239,7 @@ async function _fetch_with_backoff(url, max_retries, base_delay, max_delay, corr
             if (response.status === 200) {
                 log_trace(correlation_id, `Successfully fetched data from ${url} on attempt ${attempt}`);
                 const arrayBuffer = await response.arrayBuffer();
-                return arrayBuffer;
+                return new Uint8Array(arrayBuffer);
             } else {
                 throw new Error(`Failed to fetch: ${response.status} ${response.statusText}`);
             }
@@ -306,25 +269,26 @@ function _get_payload_bytes(data) {
     }
 }
 
-// MessagePayload class
+// MessagePayload class - matches msg_payload_v1 Julia struct
 class MessagePayload {
     /**
      * Represents a single payload in the message envelope
+     * Matches Julia's msg_payload_v1 struct
      * 
      * @param {Object} options - Payload options
      * @param {string} options.id - ID of this payload (e.g., "uuid4")
      * @param {string} options.dataname - Name of this payload (e.g., "login_image")
-     * @param {string} options.type - Payload type: "text", "dictionary", "table", "image", "audio", "video", "binary"
+     * @param {string} options.payload_type - Payload type: "text", "dictionary", "table", "image", "audio", "video", "binary"
      * @param {string} options.transport - "direct" or "link"
      * @param {string} options.encoding - "none", "json", "base64", "arrow-ipc"
      * @param {number} options.size - Data size in bytes
-     * @param {string|ArrayBuffer} options.data - Payload data (direct) or URL (link)
+     * @param {string|Uint8Array} options.data - Payload data (Uint8Array for direct, URL string for link)
      * @param {Object} options.metadata - Metadata for this payload
      */
     constructor(options) {
         this.id = options.id || uuid4();
         this.dataname = options.dataname;
-        this.type = options.type;
+        this.payload_type = options.payload_type;
         this.transport = options.transport;
         this.encoding = options.encoding;
         this.size = options.size;
@@ -332,27 +296,27 @@ class MessagePayload {
         this.metadata = options.metadata || {};
     }
     
-    // Convert to JSON object
+    // Convert to JSON object - uses snake_case to match Julia API
     toJSON() {
         const obj = {
             id: this.id,
             dataname: this.dataname,
-            type: this.type,
+            payload_type: this.payload_type,
             transport: this.transport,
             encoding: this.encoding,
             size: this.size
         };
         
         // Include data based on transport type
-        if (this.transport === "direct" && this.data !== null) {
+        if (this.transport === "direct" && this.data !== null && this.data !== undefined) {
             if (this.encoding === "base64" || this.encoding === "json") {
                 obj.data = this.data;
             } else {
                 // For other encodings, use base64
                 const payloadBytes = _get_payload_bytes(this.data);
-                obj.data = arrayBufferToBase64(payloadBytes);
+                obj.data = uint8ArrayToBase64(payloadBytes);
             }
-        } else if (this.transport === "link" && this.data !== null) {
+        } else if (this.transport === "link" && this.data !== null && this.data !== undefined) {
             // For link transport, data is a URL string
             obj.data = this.data;
         }
@@ -365,59 +329,60 @@ class MessagePayload {
     }
 }
 
-// MessageEnvelope class
+// MessageEnvelope class - matches msg_envelope_v1 Julia struct
 class MessageEnvelope {
     /**
      * Represents the message envelope containing metadata and payloads
+     * Matches Julia's msg_envelope_v1 struct
      * 
      * @param {Object} options - Envelope options
-     * @param {string} options.sendTo - Topic/subject the sender sends to
+     * @param {string} options.correlation_id - Unique identifier to track messages
-     * @param {Array<MessagePayload>} options.payloads - Array of payloads
+     * @param {string} options.msg_id - This message id
-     * @param {string} options.correlationId - Unique identifier to track messages
-     * @param {string} options.msgId - This message id
      * @param {string} options.timestamp - Message published timestamp
-     * @param {string} options.msgPurpose - Purpose of this message
+     * @param {string} options.send_to - Topic/subject the sender sends to
-     * @param {string} options.senderName - Name of the sender
+     * @param {string} options.msg_purpose - Purpose of this message
-     * @param {string} options.senderId - UUID of the sender
+     * @param {string} options.sender_name - Name of the sender
-     * @param {string} options.receiverName - Name of the receiver
+     * @param {string} options.sender_id - UUID of the sender
-     * @param {string} options.receiverId - UUID of the receiver
+     * @param {string} options.receiver_name - Name of the receiver
-     * @param {string} options.replyTo - Topic to reply to
+     * @param {string} options.receiver_id - UUID of the receiver
-     * @param {string} options.replyToMsgId - Message id this message is replying to
+     * @param {string} options.reply_to - Topic to reply to
-     * @param {string} options.brokerURL - NATS server address
+     * @param {string} options.reply_to_msg_id - Message id this message is replying to
+     * @param {string} options.broker_url - NATS server address
      * @param {Object} options.metadata - Metadata for the envelope
+     * @param {Array<MessagePayload>} options.payloads - Array of payloads
      */
     constructor(options) {
-        this.correlationId = options.correlationId || uuid4();
+        this.correlation_id = options.correlation_id || uuid4();
-        this.msgId = options.msgId || uuid4();
+        this.msg_id = options.msg_id || uuid4();
         this.timestamp = options.timestamp || new Date().toISOString();
-        this.sendTo = options.sendTo;
+        this.send_to = options.send_to;
-        this.msgPurpose = options.msgPurpose || "";
+        this.msg_purpose = options.msg_purpose || "";
-        this.senderName = options.senderName || "";
+        this.sender_name = options.sender_name || "";
-        this.senderId = options.senderId || uuid4();
+        this.sender_id = options.sender_id || uuid4();
-        this.receiverName = options.receiverName || "";
+        this.receiver_name = options.receiver_name || "";
-        this.receiverId = options.receiverId || "";
+        this.receiver_id = options.receiver_id || "";
-        this.replyTo = options.replyTo || "";
+        this.reply_to = options.reply_to || "";
-        this.replyToMsgId = options.replyToMsgId || "";
+        this.reply_to_msg_id = options.reply_to_msg_id || "";
-        this.brokerURL = options.brokerURL || DEFAULT_NATS_URL;
+        this.broker_url = options.broker_url || DEFAULT_NATS_URL;
         this.metadata = options.metadata || {};
         this.payloads = options.payloads || [];
     }
     
-    // Convert to JSON string
+    // Convert to JSON object - uses snake_case to match Julia API
     toJSON() {
         const obj = {
-            correlationId: this.correlationId,
+            correlation_id: this.correlation_id,
-            msgId: this.msgId,
+            msg_id: this.msg_id,
             timestamp: this.timestamp,
-            sendTo: this.sendTo,
+            send_to: this.send_to,
-            msgPurpose: this.msgPurpose,
+            msg_purpose: this.msg_purpose,
-            senderName: this.senderName,
+            sender_name: this.sender_name,
-            senderId: this.senderId,
+            sender_id: this.sender_id,
-            receiverName: this.receiverName,
+            receiver_name: this.receiver_name,
-            receiverId: this.receiverId,
+            receiver_id: this.receiver_id,
-            replyTo: this.replyTo,
+            reply_to: this.reply_to,
-            replyToMsgId: this.replyToMsgId,
+            reply_to_msg_id: this.reply_to_msg_id,
-            brokerURL: this.brokerURL
+            broker_url: this.broker_url
         };
         
         if (Object.keys(this.metadata).length > 0) {
@@ -437,7 +402,7 @@ class MessageEnvelope {
     }
 }
 
-// SmartSend function
+// SmartSend function - matches Julia smartsend signature and behavior
 async function smartsend(subject, data, options = {}) {
     /**
      * Send data either directly via NATS or via a fileserver URL, depending on payload size
@@ -447,40 +412,45 @@ async function smartsend(subject, data, options = {}) {
      * Otherwise, it uploads the data to a fileserver and publishes only the download URL over NATS.
      * 
      * @param {string} subject - NATS subject to publish the message to
-     * @param {Array} data - List of {dataname, data, type} objects to send
+     * @param {Array} data - List of {dataname, data, type} objects to send (must be a list, even for single payload)
      * @param {Object} options - Additional options
-     * @param {string} options.natsUrl - URL of the NATS server (default: "nats://localhost:4222")
+     * @param {string} options.broker_url - URL of the NATS server (default: "nats://localhost:4222")
-     * @param {string} options.fileserverUrl - Base URL of the file server (default: "http://localhost:8080")
+     * @param {string} options.fileserver_url - Base URL of the file server (default: "http://localhost:8080")
-     * @param {Function} options.fileserverUploadHandler - Function to handle fileserver uploads
+     * @param {Function} options.fileserver_upload_handler - Function to handle fileserver uploads
-     * @param {number} options.sizeThreshold - Threshold in bytes separating direct vs link transport (default: 1MB)
+     * @param {number} options.size_threshold - Threshold in bytes separating direct vs link transport (default: 1MB)
-     * @param {string} options.correlationId - Optional correlation ID for tracing
+     * @param {string} options.correlation_id - Optional correlation ID for tracing
-     * @param {string} options.msgPurpose - Purpose of the message (default: "chat")
+     * @param {string} options.msg_purpose - Purpose of the message (default: "chat")
-     * @param {string} options.senderName - Name of the sender (default: "NATSBridge")
+     * @param {string} options.sender_name - Name of the sender (default: "NATSBridge")
-     * @param {string} options.receiverName - Name of the receiver (default: "")
+     * @param {string} options.receiver_name - Name of the receiver (default: "")
-     * @param {string} options.receiverId - UUID of the receiver (default: "")
+     * @param {string} options.receiver_id - UUID of the receiver (default: "")
-     * @param {string} options.replyTo - Topic to reply to (default: "")
+     * @param {string} options.reply_to - Topic to reply to (default: "")
-     * @param {string} options.replyToMsgId - Message ID this message is replying to (default: "")
+ * @param {string} options.reply_to_msg_id - Message ID this message is replying to (default: "")
-     * 
+ * @param {boolean} options.is_publish - Whether to automatically publish the message to NATS (default: true)
-     * @returns {Promise<MessageEnvelope>} - The envelope for tracking
+ *   - When true: Message is published to NATS automatically
-     */
+ *   - When false: Returns (env, env_json_str) without publishing, allowing manual publishing
+ * @returns {Promise<Object>} - A tuple-like object with { env: MessageEnvelope, env_json_str: string }
+ *   - env: MessageEnvelope object with all metadata and payloads
+ *   - env_json_str: JSON string representation of the envelope for manual publishing
+ */
     const {
-        natsUrl = DEFAULT_NATS_URL,
+        broker_url = DEFAULT_NATS_URL,
-        fileserverUrl = DEFAULT_FILESERVER_URL,
+        fileserver_url = DEFAULT_FILESERVER_URL,
-        fileserverUploadHandler = _upload_to_fileserver,
+        fileserver_upload_handler = _upload_to_fileserver,
-        sizeThreshold = DEFAULT_SIZE_THRESHOLD,
+        size_threshold = DEFAULT_SIZE_THRESHOLD,
-        correlationId = uuid4(),
+        correlation_id = uuid4(),
-        msgPurpose = "chat",
+        msg_purpose = "chat",
-        senderName = "NATSBridge",
+        sender_name = "NATSBridge",
-        receiverName = "",
+        receiver_name = "",
-        receiverId = "",
+        receiver_id = "",
-        replyTo = "",
+        reply_to = "",
-        replyToMsgId = ""
+        reply_to_msg_id = "",
+        is_publish = true  // Whether to automatically publish the message to NATS
     } = options;
     
-    log_trace(correlationId, `Starting smartsend for subject: ${subject}`);
+    log_trace(correlation_id, `Starting smartsend for subject: ${subject}`);
     
     // Generate message metadata
-    const msgId = uuid4();
+    const msg_id = uuid4();
     
     // Process each payload in the list
     const payloads = [];
@@ -494,18 +464,18 @@ async function smartsend(subject, data, options = {}) {
         const payloadBytes = _serialize_data(payloadData, payloadType);
         const payloadSize = payloadBytes.byteLength;
         
-        log_trace(correlationId, `Serialized payload '${dataname}' (type: ${payloadType}) size: ${payloadSize} bytes`);
+        log_trace(correlation_id, `Serialized payload '${dataname}' (payload_type: ${payloadType}) size: ${payloadSize} bytes`);
         
         // Decision: Direct vs Link
-        if (payloadSize < sizeThreshold) {
+        if (payloadSize < size_threshold) {
             // Direct path - Base64 encode and send via NATS
-            const payloadB64 = arrayBufferToBase64(payloadBytes);
+            const payloadB64 = uint8ArrayToBase64(payloadBytes);
-            log_trace(correlationId, `Using direct transport for ${payloadSize} bytes`);
+            log_trace(correlation_id, `Using direct transport for ${payloadSize} bytes`);
             
             // Create MessagePayload for direct transport
             const payloadObj = new MessagePayload({
                 dataname: dataname,
-                type: payloadType,
+                payload_type: payloadType,
                 transport: "direct",
                 encoding: "base64",
                 size: payloadSize,
@@ -515,22 +485,22 @@ async function smartsend(subject, data, options = {}) {
             payloads.push(payloadObj);
         } else {
             // Link path - Upload to HTTP server, send URL via NATS
-            log_trace(correlationId, `Using link transport, uploading to fileserver`);
+            log_trace(correlation_id, `Using link transport, uploading to fileserver`);
             
-            // Upload to HTTP server
+            // Upload to HTTP server using plik_oneshot_upload handler
-            const response = await fileserverUploadHandler(fileserverUrl, dataname, payloadBytes, correlationId);
+            const response = await fileserver_upload_handler(fileserver_url, dataname, payloadBytes);
             
             if (response.status !== 200) {
                 throw new Error(`Failed to upload data to fileserver: ${response.status}`);
             }
             
             const url = response.url;
-            log_trace(correlationId, `Uploaded to URL: ${url}`);
+            log_trace(correlation_id, `Uploaded to URL: ${url}`);
             
             // Create MessagePayload for link transport
             const payloadObj = new MessagePayload({
                 dataname: dataname,
-                type: payloadType,
+                payload_type: payloadType,
                 transport: "link",
                 encoding: "none",
                 size: payloadSize,
@@ -543,31 +513,40 @@ async function smartsend(subject, data, options = {}) {
     
     // Create MessageEnvelope with all payloads
     const env = new MessageEnvelope({
-        correlationId: correlationId,
+        correlation_id: correlation_id,
-        msgId: msgId,
+        msg_id: msg_id,
-        sendTo: subject,
+        send_to: subject,
-        msgPurpose: msgPurpose,
+        msg_purpose: msg_purpose,
-        senderName: senderName,
+        sender_name: sender_name,
-        receiverName: receiverName,
+        receiver_name: receiver_name,
-        receiverId: receiverId,
+        receiver_id: receiver_id,
-        replyTo: replyTo,
+        reply_to: reply_to,
-        replyToMsgId: replyToMsgId,
+        reply_to_msg_id: reply_to_msg_id,
-        brokerURL: natsUrl,
+        broker_url: broker_url,
         payloads: payloads
     });
     
-    // Publish message to NATS
+    // Convert envelope to JSON string
-    await publish_message(natsUrl, subject, env.toString(), correlationId);
+    const env_json_str = env.toString();
     
-    return env;
+    // Publish to NATS if isPublish is true
+    if (is_publish) {
+        await publish_message(broker_url, subject, env_json_str, correlation_id);
+    }
+    
+    // Return both envelope and JSON string (tuple-like structure, matching Julia API)
+    return {
+        env: env,
+        env_json_str: env_json_str
+    };
 }
 
 // Helper: Publish message to NATS
-async function publish_message(natsUrl, subject, message, correlation_id) {
+async function publish_message(broker_url, subject, message, correlation_id) {
     /**
      * Publish a message to a NATS subject with proper connection management
      * 
-     * @param {string} natsUrl - NATS server URL
+     * @param {string} broker_url - NATS server URL
      * @param {string} subject - NATS subject to publish to
      * @param {string} message - JSON message to publish
      * @param {string} correlation_id - Correlation ID for logging
@@ -580,7 +559,7 @@ async function publish_message(natsUrl, subject, message, correlation_id) {
     
     // Example with nats.js:
     // import { connect } from 'nats';
-    // const nc = await connect({ servers: [natsUrl] });
+    // const nc = await connect({ servers: [broker_url] });
     // await nc.publish(subject, message);
     // nc.close();
     
@@ -588,7 +567,7 @@ async function publish_message(natsUrl, subject, message, correlation_id) {
     console.log(`[NATS PUBLISH] Subject: ${subject}, Message: ${message.substring(0, 100)}...`);
 }
 
-// SmartReceive function
+// SmartReceive function - matches Julia smartreceive signature and behavior
 async function smartreceive(msg, options = {}) {
     /**
      * Receive and process messages from NATS
@@ -598,25 +577,25 @@ async function smartreceive(msg, options = {}) {
      * 
      * @param {Object} msg - NATS message object with payload property
      * @param {Object} options - Additional options
-     * @param {Function} options.fileserverDownloadHandler - Function to handle downloading data from file server URLs
+     * @param {Function} options.fileserver_download_handler - Function to handle downloading data from file server URLs
-     * @param {number} options.maxRetries - Maximum retry attempts for fetching URL (default: 5)
+     * @param {number} options.max_retries - Maximum retry attempts for fetching URL (default: 5)
-     * @param {number} options.baseDelay - Initial delay for exponential backoff in ms (default: 100)
+     * @param {number} options.base_delay - Initial delay for exponential backoff in ms (default: 100)
-     * @param {number} options.maxDelay - Maximum delay for exponential backoff in ms (default: 5000)
+     * @param {number} options.max_delay - Maximum delay for exponential backoff in ms (default: 5000)
      * 
-     * @returns {Promise<Object>} - Envelope dictionary with metadata and payloads field containing list of {dataname, data, type} objects
+     * @returns {Promise<Object>} - JSON object of envelope with payloads field containing list of {dataname, data, type} tuples
      */
     const {
-        fileserverDownloadHandler = _fetch_with_backoff,
+        fileserver_download_handler = _fetch_with_backoff,
-        maxRetries = 5,
+        max_retries = 5,
-        baseDelay = 100,
+        base_delay = 100,
-        maxDelay = 5000
+        max_delay = 5000
     } = options;
     
     // Parse the JSON envelope
     const jsonStr = typeof msg.payload === 'string' ? msg.payload : new TextDecoder().decode(msg.payload);
     const json_data = JSON.parse(jsonStr);
     
-    log_trace(json_data.correlationId, `Processing received message`);
+    log_trace(json_data.correlation_id, `Processing received message`);
     
     // Process all payloads in the envelope
     const payloads_list = [];
@@ -631,32 +610,32 @@ async function smartreceive(msg, options = {}) {
         
         if (transport === "direct") {
             // Direct transport - payload is in the message
-            log_trace(json_data.correlationId, `Direct transport - decoding payload '${dataname}'`);
+            log_trace(json_data.correlation_id, `Direct transport - decoding payload '${dataname}'`);
             
             // Extract base64 payload from the payload
             const payload_b64 = payload.data;
             
             // Decode Base64 payload
-            const payload_bytes = base64ToArrayBuffer(payload_b64);
+            const payload_bytes = base64ToUint8Array(payload_b64);
             
             // Deserialize based on type
-            const data_type = payload.type;
+            const data_type = payload.payload_type;
-            const data = _deserialize_data(payload_bytes, data_type, json_data.correlationId);
+            const data = _deserialize_data(payload_bytes, data_type, json_data.correlation_id);
             
             payloads_list.push({ dataname, data, type: data_type });
         } else if (transport === "link") {
             // Link transport - payload is at URL
             const url = payload.data;
-            log_trace(json_data.correlationId, `Link transport - fetching '${dataname}' from URL: ${url}`);
+            log_trace(json_data.correlation_id, `Link transport - fetching '${dataname}' from URL: ${url}`);
             
             // Fetch with exponential backoff using the download handler
-            const downloaded_data = await fileserverDownloadHandler(
+            const downloaded_data = await fileserver_download_handler(
-                url, maxRetries, baseDelay, maxDelay, json_data.correlationId
+                url, max_retries, base_delay, max_delay, json_data.correlation_id
             );
             
             // Deserialize based on type
-            const data_type = payload.type;
+            const data_type = payload.payload_type;
-            const data = _deserialize_data(downloaded_data, data_type, json_data.correlationId);
+            const data = _deserialize_data(downloaded_data, data_type, json_data.correlation_id);
             
             payloads_list.push({ dataname, data, type: data_type });
         } else {
@@ -665,11 +644,74 @@ async function smartreceive(msg, options = {}) {
     }
     
     // Replace payloads array with the processed list of {dataname, data, type} tuples
+    // This matches Julia's smartreceive return format
     json_data.payloads = payloads_list;
     
     return json_data;
 }
 
+// plik_oneshot_upload - matches Julia plik_oneshot_upload function
+// Upload handler signature: plik_oneshot_upload(fileserver_url, dataname, data)
+// Returns: { status, uploadid, fileid, url }
+async function plik_oneshot_upload(file_server_url, dataname, data) {
+    /**
+     * Upload a single file to a plik server using one-shot mode
+     * This function uploads raw byte array to a plik server in one-shot mode (no upload session).
+     * It first creates a one-shot upload session by sending a POST request with {"OneShot": true},
+     * retrieves an upload ID and token, then uploads the file data as multipart form data using the token.
+     *
+     * This is the default upload handler used by smartsend.
+     * Custom handlers can be passed via the fileserver_upload_handler option.
+     *
+     * @param {string} file_server_url - Base URL of the plik server (e.g., "http://localhost:8080")
+     * @param {string} dataname - Name of the file being uploaded
+     * @param {Uint8Array} data - Raw byte data of the file content
+     * @returns {Promise<Object>} - Dictionary with keys: status, uploadid, fileid, url
+     */
+    
+    // Step 1: Get upload ID and token
+    const url_getUploadID = `${file_server_url}/upload`;
+    const headers = { "Content-Type": "application/json" };
+    const body = JSON.stringify({ OneShot: true });
+    
+    let http_response = await fetch(url_getUploadID, {
+        method: "POST",
+        headers: headers,
+        body: body
+    });
+    
+    const response_json = await http_response.json();
+    const uploadid = response_json.id;
+    const uploadtoken = response_json.uploadToken;
+    
+    // Step 2: Upload file data
+    const url_upload = `${file_server_url}/file/${uploadid}`;
+    
+    // Create multipart form data
+    const formData = new FormData();
+    const blob = new Blob([data], { type: "application/octet-stream" });
+    formData.append("file", blob, dataname);
+    
+    http_response = await fetch(url_upload, {
+        method: "POST",
+        headers: { "X-UploadToken": uploadtoken },
+        body: formData
+    });
+    
+    const fileResponseJson = await http_response.json();
+    const fileid = fileResponseJson.id;
+    
+    // URL of the uploaded data e.g. "http://192.168.1.20:8080/file/3F62E/4AgGT/test.zip"
+    const url = `${file_server_url}/file/${uploadid}/${fileid}/${encodeURIComponent(dataname)}`;
+    
+    return {
+        status: http_response.status,
+        uploadid: uploadid,
+        fileid: fileid,
+        url: url
+    };
+}
+
 // Export for Node.js
 if (typeof module !== 'undefined' && module.exports) {
     module.exports = {
@@ -681,6 +723,7 @@ if (typeof module !== 'undefined' && module.exports) {
         _deserialize_data,
         _fetch_with_backoff,
         _upload_to_fileserver,
+        plik_oneshot_upload,
         DEFAULT_SIZE_THRESHOLD,
         DEFAULT_NATS_URL,
         DEFAULT_FILESERVER_URL,
@@ -700,6 +743,7 @@ if (typeof window !== 'undefined') {
         _deserialize_data,
         _fetch_with_backoff,
         _upload_to_fileserver,
+        plik_oneshot_upload,
         DEFAULT_SIZE_THRESHOLD,
         DEFAULT_NATS_URL,
         DEFAULT_FILESERVER_URL,

src/README.md

@@ -1,295 +0,0 @@
-# NATSBridge
-
-A high-performance, bi-directional data bridge for **Julia**, **JavaScript**, and **Python/Micropython** using NATS (Core & JetStream), implementing the Claim-Check pattern for large payloads.
-
-## Overview
-
-NATSBridge enables seamless communication between Julia, JavaScript, and Python/Micropython applications through NATS, with automatic transport selection based on payload size:
-
-- **Direct Transport**: Payloads < 1MB are sent directly via NATS (Base64 encoded)
-- **Link Transport**: Payloads >= 1MB are uploaded to an HTTP file server and referenced via URL
-
-## Features
-
-- ✅ Bi-directional NATS communication across Julia ↔ JavaScript ↔ Python/Micropython
-- ✅ Multi-payload support (mixed content in single message)
-- ✅ Automatic transport selection based on payload size
-- ✅ File server integration for large payloads
-- ✅ Exponential backoff for URL fetching
-- ✅ Correlation ID tracking
-- ✅ Reply-to support for request-response pattern
-
-## Supported Payload Types
-
-| Type | Description |
-|------|-------------|
-| `text` | Plain text strings |
-| `dictionary` | JSON-serializable dictionaries |
-| `table` | Tabular data (Arrow IPC format) |
-| `image` | Image data (PNG, JPG bytes) |
-| `audio` | Audio data (WAV, MP3 bytes) |
-| `video` | Video data (MP4, AVI bytes) |
-| `binary` | Generic binary data |
-
-## Implementation Guides
-
-### [Julia Implementation](../tutorial_julia.md)
-
-See the [Julia tutorial](../tutorial_julia.md) for getting started with Julia.
-
-### [JavaScript Implementation](#javascript-implementation)
-
-See [`NATSBridge.js`](NATSBridge.js) for the JavaScript implementation.
-
-### [Python/Micropython Implementation](#pythonmicropython-implementation)
-
-See [`nats_bridge.py`](nats_bridge.py) for the Python/Micropython implementation.
-
-## Installation
-
-### Julia
-
-```julia
-using Pkg
-Pkg.add("NATS")
-Pkg.add("Arrow")
-Pkg.add("JSON3")
-Pkg.add("HTTP")
-Pkg.add("UUIDs")
-Pkg.add("Dates")
-```
-
-### JavaScript
-
-```bash
-npm install nats.js apache-arrow uuid base64-url
-```
-
-### Python/Micropython
-
-1. Copy `nats_bridge.py` to your device
-2. Ensure you have the following dependencies:
-   - `urequests` for HTTP requests (Micropython)
-   - `requests` for HTTP requests (Python)
-   - `base64` for base64 encoding
-   - `json` for JSON handling
-   - `socket` for networking (Micropython)
-
-## Usage
-
-### Basic Text Message
-
-#### Python/Micropython
-
-```python
-from nats_bridge import smartsend, smartreceive
-
-# Sender
-data = [("message", "Hello World", "text")]
-env = smartsend("/chat/room1", data, nats_url="nats://localhost:4222")
-
-# Receiver
-payloads = smartreceive(msg)
-for dataname, data, type in payloads:
-    print("Received {}: {}".format(dataname, data))
-```
-
-#### Julia
-
-```julia
-using NATSBridge
-
-# Sender
-data = [("message", "Hello World", "text")]
-env = smartsend("/chat/room1", data, nats_url="nats://localhost:4222")
-
-# Receiver
-envelope = smartreceive(msg, fileserverDownloadHandler)
-# envelope["payloads"] = [("message", "Hello World", "text"), ...]
-```
-
-#### JavaScript
-
-```javascript
-const { smartsend, smartreceive } = require('./src/NATSBridge');
-
-// Sender
-await smartsend("/chat/room1", [
-    { dataname: "message", data: "Hello World", type: "text" }
-], { natsUrl: "nats://localhost:4222" });
-
-// Receiver
-const envelope = await smartreceive(msg);
-// envelope.payloads = [{ dataname: "message", data: "Hello World", type: "text" }, ...]
-```
-
-### Sending JSON Configuration
-
-#### Python/Micropython
-
-```python
-from nats_bridge import smartsend
-
-config = {
-    "wifi_ssid": "MyNetwork",
-    "wifi_password": "password123",
-    "update_interval": 60
-}
-
-data = [("config", config, "dictionary")]
-env = smartsend("/device/config", data, nats_url="nats://localhost:4222")
-```
-
-### Mixed Content (Chat with Text + Image)
-
-#### Python/Micropython
-
-```python
-from nats_bridge import smartsend
-
-image_data = b"\x89PNG..."  # PNG bytes
-
-data = [
-    ("message_text", "Hello with image!", "text"),
-    ("user_avatar", image_data, "binary")
-]
-
-env = smartsend("/chat/mixed", data, nats_url="nats://localhost:4222")
-```
-
-### Request-Response Pattern
-
-#### Python/Micropython
-
-```python
-from nats_bridge import smartsend
-
-# Send command with reply-to
-data = [("command", {"action": "read_sensor"}, "dictionary")]
-env = smartsend(
-    "/device/command",
-    data,
-    nats_url="nats://localhost:4222",
-    reply_to="/device/response",
-    reply_to_msg_id="cmd-001"
-)
-```
-
-### Large Payloads (File Server)
-
-#### Python/Micropython
-
-```python
-from nats_bridge import smartsend
-
-# Large data (> 1MB)
-large_data = b"A" * 2000000  # 2MB
-
-env = smartsend(
-    "/data/large",
-    [("large_file", large_data, "binary")],
-    nats_url="nats://localhost:4222",
-    fileserver_url="http://localhost:8080",
-    size_threshold=1000000  # 1MB threshold
-)
-```
-
-## API Reference
-
-### `smartsend(subject, data, ...)`
-
-Send data via NATS with automatic transport selection.
-
-**Arguments:**
-- `subject` (str): NATS subject to publish to
-- `data` (list): List of `(dataname, data, type)` tuples
-- `nats_url` (str): NATS server URL (default: `nats://localhost:4222`)
-- `fileserver_url` (str): HTTP file server URL (default: `http://localhost:8080`)
-- `size_threshold` (int): Threshold in bytes (default: 1,000,000)
-- `correlation_id` (str): Optional correlation ID for tracing
-- `msg_purpose` (str): Message purpose (default: `"chat"`)
-- `sender_name` (str): Sender name (default: `"NATSBridge"`)
-- `receiver_name` (str): Receiver name (default: `""`)
-- `receiver_id` (str): Receiver ID (default: `""`)
-- `reply_to` (str): Reply topic (default: `""`)
-- `reply_to_msg_id` (str): Reply message ID (default: `""`)
-
-**Returns:** `MessageEnvelope` object
-
-### `smartreceive(msg, ...)`
-
-Receive and process NATS messages.
-
-**Arguments:**
-- `msg`: NATS message (dict or JSON string)
-- `fileserver_download_handler` (function): Function to fetch data from URLs
-- `max_retries` (int): Maximum retry attempts (default: 5)
-- `base_delay` (int): Initial delay in ms (default: 100)
-- `max_delay` (int): Maximum delay in ms (default: 5000)
-
-**Returns:** List of `(dataname, data, type)` tuples
-
-### `MessageEnvelope`
-
-Represents a complete NATS message envelope.
-
-**Attributes:**
-- `correlation_id`: Unique identifier for tracing
-- `msg_id`: Unique message identifier
-- `timestamp`: Message publication timestamp
-- `send_to`: NATS subject
-- `msg_purpose`: Message purpose
-- `sender_name`: Sender name
-- `sender_id`: Sender UUID
-- `receiver_name`: Receiver name
-- `receiver_id`: Receiver UUID
-- `reply_to`: Reply topic
-- `reply_to_msg_id`: Reply message ID
-- `broker_url`: NATS broker URL
-- `metadata`: Message-level metadata
-- `payloads`: List of MessagePayload objects
-
-### `MessagePayload`
-
-Represents a single payload within a message envelope.
-
-**Attributes:**
-- `id`: Unique payload identifier
-- `dataname`: Name of the payload
-- `type`: Payload type ("text", "dictionary", etc.)
-- `transport`: Transport method ("direct" or "link")
-- `encoding`: Encoding method ("none", "base64", etc.)
-- `size`: Payload size in bytes
-- `data`: Payload data (bytes for direct, URL for link)
-- `metadata`: Payload-level metadata
-
-## Examples
-
-See [`examples/micropython_example.py`](../examples/micropython_example.py) for more detailed examples.
-
-## Testing
-
-Run the test suite:
-
-```bash
-# Python/Micropython
-python test/test_micropython_basic.py
-
-# JavaScript
-node test/test_js_to_js_text_sender.js
-node test/test_js_to_js_text_receiver.js
-
-# Julia
-julia test/test_julia_to_julia_text_sender.jl
-julia test/test_julia_to_julia_text_receiver.jl
-```
-
-## Requirements
-
-- **Julia**: NATS server (nats.io), HTTP file server (optional)
-- **JavaScript**: NATS server (nats.io), HTTP file server (optional)
-- **Python/Micropython**: NATS server (nats.io), HTTP file server (optional)
-
-## License
-
-MIT

src/nats_bridge.py

@@ -1,45 +1,60 @@
 """
-Micropython NATS Bridge - Bi-Directional Data Bridge for Micropython
+Python NATS Bridge - Bi-Directional Data Bridge
 
 This module provides functionality for sending and receiving data over NATS
 using the Claim-Check pattern for large payloads.
 
 Supported types: "text", "dictionary", "table", "image", "audio", "video", "binary"
+
+Multi-Payload Support (Standard API):
+The system uses a standardized list-of-tuples format for all payload operations.
+Even when sending a single payload, the user must wrap it in a list.
+
+API Standard:
+    # Input format for smartsend (always a list of tuples with type info)
+    [(dataname1, data1, type1), (dataname2, data2, type2), ...]
+    
+    # Output format for smartreceive (always returns a list of tuples)
+    [(dataname1, data1, type1), (dataname2, data2, type2), ...]
 """
 
 import json
-import random
 import time
-import usocket
-import uselect
-import ustruct
 import uuid
 
-try:
-    import ussl
-    HAS_SSL = True
-except ImportError:
-    HAS_SSL = False
-
 # Constants
 DEFAULT_SIZE_THRESHOLD = 1000000  # 1MB - threshold for switching from direct to link transport
-DEFAULT_NATS_URL = "nats://localhost:4222"
+DEFAULT_BROKER_URL = "nats://localhost:4222"
 DEFAULT_FILESERVER_URL = "http://localhost:8080"
 
 # ============================================= 100 ============================================== #
 
 
 class MessagePayload:
-    """Internal message payload structure representing a single payload within a NATS message envelope."""
+    """Internal message payload structure representing a single payload within a NATS message envelope.
     
-    def __init__(self, data, msg_type, id="", dataname="", transport="direct", 
+    This structure represents a single payload within a NATS message envelope.
+    It supports both direct transport (base64-encoded data) and link transport (URL-based).
+    
+    Attributes:
+        id: Unique identifier for this payload (e.g., "uuid4")
+        dataname: Name of the payload (e.g., "login_image")
+        payload_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+        transport: Transport method ("direct" or "link")
+        encoding: Encoding method ("none", "json", "base64", "arrow-ipc")
+        size: Size of the payload in bytes
+        data: Payload data (bytes for direct, URL for link)
+        metadata: Optional metadata dictionary
+    """
+    
+    def __init__(self, data, payload_type, id="", dataname="", transport="direct", 
                  encoding="none", size=0, metadata=None):
         """
         Initialize a MessagePayload.
         
         Args:
-            data: Payload data (bytes for direct, URL string for link)
+            data: Payload data (base64 string for direct, URL string for link)
-            msg_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+            payload_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
             id: Unique identifier for this payload (auto-generated if empty)
             dataname: Name of the payload (auto-generated UUID if empty)
             transport: Transport method ("direct" or "link")
@@ -49,7 +64,7 @@ class MessagePayload:
         """
         self.id = id if id else self._generate_uuid()
         self.dataname = dataname if dataname else self._generate_uuid()
-        self.type = msg_type
+        self.payload_type = payload_type
         self.transport = transport
         self.encoding = encoding
         self.size = size
@@ -65,7 +80,7 @@ class MessagePayload:
         payload_dict = {
             "id": self.id,
             "dataname": self.dataname,
-            "type": self.type,
+            "payload_type": self.payload_type,
             "transport": self.transport,
             "encoding": self.encoding,
             "size": self.size,
@@ -152,20 +167,24 @@ class MessageEnvelope:
         return "2026-02-21T" + time.strftime("%H:%M:%S", time.localtime())
     
     def to_json(self):
-        """Convert envelope to JSON string."""
+        """Convert envelope to JSON string.
+        
+        Returns:
+            str: JSON string representation of the envelope using snake_case field names
+        """
         obj = {
-            "correlationId": self.correlation_id,
+            "correlation_id": self.correlation_id,
-            "msgId": self.msg_id,
+            "msg_id": self.msg_id,
             "timestamp": self.timestamp,
-            "sendTo": self.send_to,
+            "send_to": self.send_to,
-            "msgPurpose": self.msg_purpose,
+            "msg_purpose": self.msg_purpose,
-            "senderName": self.sender_name,
+            "sender_name": self.sender_name,
-            "senderId": self.sender_id,
+            "sender_id": self.sender_id,
-            "receiverName": self.receiver_name,
+            "receiver_name": self.receiver_name,
-            "receiverId": self.receiver_id,
+            "receiver_id": self.receiver_id,
-            "replyTo": self.reply_to,
+            "reply_to": self.reply_to,
-            "replyToMsgId": self.reply_to_msg_id,
+            "reply_to_msg_id": self.reply_to_msg_id,
-            "brokerURL": self.broker_url
+            "broker_url": self.broker_url
         }
         
         # Include metadata if not empty
@@ -188,68 +207,126 @@ def log_trace(correlation_id, message):
     print("[{}] [Correlation: {}] {}".format(timestamp, correlation_id, message))
 
 
-def _serialize_data(data, msg_type):
+def _serialize_data(data, payload_type):
     """Serialize data according to specified format.
     
+    This function serializes arbitrary data into a binary representation based on the specified type.
+    It supports multiple serialization formats for different data types.
+    
     Args:
         data: Data to serialize
-        msg_type: Target format ("text", "dictionary", "table", "image", "audio", "video", "binary")
+            - "text": String
+            - "dictionary": JSON-serializable dict
+            - "table": Tabular data (pandas DataFrame or list of dicts)
+            - "image", "audio", "video", "binary": bytes
+        payload_type: Target format ("text", "dictionary", "table", "image", "audio", "video", "binary")
     
     Returns:
         bytes: Binary representation of the serialized data
+    
+    Example:
+        >>> text_bytes = _serialize_data("Hello World", "text")
+        >>> json_bytes = _serialize_data({"key": "value"}, "dictionary")
+        >>> table_bytes = _serialize_data([{"id": 1, "name": "Alice"}], "table")
     """
-    if msg_type == "text":
+    if payload_type == "text":
         if isinstance(data, str):
             return data.encode('utf-8')
         else:
             raise ValueError("Text data must be a string")
     
-    elif msg_type == "dictionary":
+    elif payload_type == "dictionary":
         if isinstance(data, dict):
             json_str = json.dumps(data)
             return json_str.encode('utf-8')
         else:
             raise ValueError("Dictionary data must be a dict")
     
-    elif msg_type in ("image", "audio", "video", "binary"):
+    elif payload_type == "table":
+        # Support pandas DataFrame or list of dicts
+        try:
+            import pandas as pd
+            if isinstance(data, pd.DataFrame):
+                # Convert DataFrame to JSON and then to bytes
+                json_str = data.to_json(orient='records', force_ascii=False)
+                return json_str.encode('utf-8')
+            elif isinstance(data, list) and len(data) > 0 and isinstance(data[0], dict):
+                # List of dicts
+                json_str = json.dumps(data)
+                return json_str.encode('utf-8')
+            else:
+                raise ValueError("Table data must be a pandas DataFrame or list of dicts")
+        except ImportError:
+            # Fallback: if pandas not available, treat as list of dicts
+            if isinstance(data, list):
+                json_str = json.dumps(data)
+                return json_str.encode('utf-8')
+            else:
+                raise ValueError("Table data requires pandas DataFrame or list of dicts (pandas not available)")
+    
+    elif payload_type in ("image", "audio", "video", "binary"):
         if isinstance(data, bytes):
             return data
         else:
-            raise ValueError("{} data must be bytes".format(msg_type.capitalize()))
+            raise ValueError("{} data must be bytes".format(payload_type.capitalize()))
     
     else:
-        raise ValueError("Unknown type: {}".format(msg_type))
+        raise ValueError("Unknown payload_type: {}".format(payload_type))
 
 
-def _deserialize_data(data_bytes, msg_type, correlation_id):
+def _deserialize_data(data_bytes, payload_type, correlation_id):
     """Deserialize bytes to data based on type.
     
+    This function converts serialized bytes back to Python data based on type.
+    It handles "text" (string), "dictionary" (JSON deserialization), "table" (JSON deserialization),
+    "image" (binary data), "audio" (binary data), "video" (binary data), and "binary" (binary data).
+    
     Args:
         data_bytes: Serialized data as bytes
-        msg_type: Data type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+        payload_type: Data type ("text", "dictionary", "table", "image", "audio", "video", "binary")
         correlation_id: Correlation ID for logging
     
     Returns:
-        Deserialized data
+        Deserialized data:
+            - "text": str
+            - "dictionary": dict
+            - "table": list of dicts (or pandas DataFrame if available)
+            - "image", "audio", "video", "binary": bytes
+    
+    Example:
+        >>> text_data = _deserialize_data(b"Hello", "text", "corr_id")
+        >>> json_data = _deserialize_data(b'{"key": "value"}', "dictionary", "corr_id")
+        >>> table_data = _deserialize_data(b'[{"id": 1}]', "table", "corr_id")
     """
-    if msg_type == "text":
+    if payload_type == "text":
         return data_bytes.decode('utf-8')
     
-    elif msg_type == "dictionary":
+    elif payload_type == "dictionary":
         json_str = data_bytes.decode('utf-8')
         return json.loads(json_str)
     
-    elif msg_type in ("image", "audio", "video", "binary"):
+    elif payload_type == "table":
+        # Deserialize table data (JSON format)
+        json_str = data_bytes.decode('utf-8')
+        table_data = json.loads(json_str)
+        # If pandas is available, try to convert to DataFrame
+        try:
+            import pandas as pd
+            return pd.DataFrame(table_data)
+        except ImportError:
+            return table_data
+    
+    elif payload_type in ("image", "audio", "video", "binary"):
         return data_bytes
     
     else:
-        raise ValueError("Unknown type: {}".format(msg_type))
+        raise ValueError("Unknown payload_type: {}".format(payload_type))
 
 
 class NATSConnection:
-    """Simple NATS connection for Micropython."""
+    """Simple NATS connection for Python and Micropython."""
     
-    def __init__(self, url=DEFAULT_NATS_URL):
+    def __init__(self, url=DEFAULT_BROKER_URL):
         """Initialize NATS connection.
         
         Args:
@@ -276,9 +353,19 @@ class NATSConnection:
     
     def connect(self):
         """Connect to NATS server."""
-        addr = usocket.getaddrinfo(self.host, self.port)[0][-1]
+        # Use socket for both Python and Micropython
-        self.conn = usocket.socket()
+        try:
-        self.conn.connect(addr)
+            import socket
+            addr = socket.getaddrinfo(self.host, self.port)[0][-1]
+            self.conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.conn.connect(addr)
+        except NameError:
+            # Micropython fallback
+            import usocket
+            addr = usocket.getaddrinfo(self.host, self.port)[0][-1]
+            self.conn = usocket.socket()
+            self.conn.connect(addr)
+        
         log_trace("", "Connected to NATS server at {}:{}".format(self.host, self.port))
     
     def publish(self, subject, message):
@@ -294,7 +381,15 @@ class NATSConnection:
         # Simple NATS protocol implementation
         msg = "PUB {} {}\r\n".format(subject, len(message))
         msg = msg.encode('utf-8') + message + b"\r\n"
-        self.conn.send(msg)
+        
+        try:
+            import socket
+            self.conn.send(msg)
+        except NameError:
+            # Micropython fallback
+            import usocket
+            self.conn.send(msg)
+        
         log_trace("", "Message published to {}".format(subject))
     
     def subscribe(self, subject, callback):
@@ -335,11 +430,14 @@ class NATSConnection:
 def _fetch_with_backoff(url, max_retries=5, base_delay=100, max_delay=5000, correlation_id=""):
     """Fetch data from URL with exponential backoff.
     
+    This function retrieves data from a URL with retry logic using
+    exponential backoff to handle transient failures.
+    
     Args:
         url: URL to fetch from
-        max_retries: Maximum number of retry attempts
+        max_retries: Maximum number of retry attempts (default: 5)
-        base_delay: Initial delay in milliseconds
+        base_delay: Initial delay in milliseconds (default: 100)
-        max_delay: Maximum delay in milliseconds
+        max_delay: Maximum delay in milliseconds (default: 5000)
         correlation_id: Correlation ID for logging
     
     Returns:
@@ -347,33 +445,54 @@ def _fetch_with_backoff(url, max_retries=5, base_delay=100, max_delay=5000, corr
     
     Raises:
         Exception: If all retry attempts fail
+    
+    Example:
+        >>> data = _fetch_with_backoff("http://example.com/file.zip", 5, 100, 5000, "corr_id")
     """
     delay = base_delay
     for attempt in range(1, max_retries + 1):
         try:
             # Simple HTTP GET request
-            # This is a simplified implementation
+            # Try urequests for Micropython first, then requests for Python
-            # For production, you'd want a proper HTTP client
+            try:
-            import urequests
+                import urequests
-            response = urequests.get(url)
+                response = urequests.get(url)
-            if response.status_code == 200:
+                status_code = response.status_code
+                content = response.content
+            except ImportError:
+                try:
+                    import requests
+                    response = requests.get(url)
+                    response.raise_for_status()
+                    status_code = response.status_code
+                    content = response.content
+                except ImportError:
+                    raise Exception("No HTTP library available (urequests or requests)")
+            
+            if status_code == 200:
                 log_trace(correlation_id, "Successfully fetched data from {} on attempt {}".format(url, attempt))
-                return response.content
+                return content
             else:
-                raise Exception("Failed to fetch: {}".format(response.status_code))
+                raise Exception("Failed to fetch: {}".format(status_code))
         except Exception as e:
             log_trace(correlation_id, "Attempt {} failed: {}".format(attempt, str(e)))
             if attempt < max_retries:
                 time.sleep(delay / 1000.0)
                 delay = min(delay * 2, max_delay)
+    
+    raise Exception("Failed to fetch data after {} attempts".format(max_retries))
 
 
-def plik_oneshot_upload(file_server_url, filename, data):
+def plik_oneshot_upload(fileserver_url, dataname, data):
     """Upload a single file to a plik server using one-shot mode.
     
+    This function uploads raw byte data to a plik server in one-shot mode (no upload session).
+    It first creates a one-shot upload session by sending a POST request with {"OneShot": true},
+    retrieves an upload ID and token, then uploads the file data as multipart form data using the token.
+    
     Args:
-        file_server_url: Base URL of the plik server
+        fileserver_url: Base URL of the plik server (e.g., "http://localhost:8080")
-        filename: Name of the file being uploaded
+        dataname: Name of the file being uploaded
         data: Raw byte data of the file content
     
     Returns:
@@ -382,23 +501,31 @@ def plik_oneshot_upload(file_server_url, filename, data):
             - "uploadid": ID of the one-shot upload session
             - "fileid": ID of the uploaded file within the session
             - "url": Full URL to download the uploaded file
+    
+    Example:
+        >>> result = plik_oneshot_upload("http://localhost:8080", "test.txt", b"hello world")
+        >>> result["status"], result["uploadid"], result["fileid"], result["url"]
     """
-    import urequests
     import json
     
+    try:
+        import urequests
+    except ImportError:
+        import requests as urequests
+    
     # Get upload ID
-    url_get_upload_id = "{}/upload".format(file_server_url)
+    url_get_upload_id = "{}/upload".format(fileserver_url)
     headers = {"Content-Type": "application/json"}
     body = json.dumps({"OneShot": True})
     
     response = urequests.post(url_get_upload_id, headers=headers, data=body)
-    response_json = json.loads(response.content)
+    response_json = json.loads(response.text if hasattr(response, 'text') else response.content)
     
     uploadid = response_json.get("id")
     uploadtoken = response_json.get("uploadToken")
     
     # Upload file
-    url_upload = "{}/file/{}".format(file_server_url, uploadid)
+    url_upload = "{}/file/{}".format(fileserver_url, uploadid)
     headers = {"X-UploadToken": uploadtoken}
     
     # For Micropython, we need to construct the multipart form data manually
@@ -407,7 +534,7 @@ def plik_oneshot_upload(file_server_url, filename, data):
     
     # Create multipart body
     part1 = "--{}\r\n".format(boundary)
-    part1 += "Content-Disposition: form-data; name=\"file\"; filename=\"{}\"\r\n".format(filename)
+    part1 += "Content-Disposition: form-data; name=\"file\"; filename=\"{}\"\r\n".format(dataname)
     part1 += "Content-Type: application/octet-stream\r\n\r\n"
     part1_bytes = part1.encode('utf-8')
     
@@ -421,10 +548,10 @@ def plik_oneshot_upload(file_server_url, filename, data):
     content_type = "multipart/form-data; boundary={}".format(boundary)
     
     response = urequests.post(url_upload, headers={"Content-Type": content_type}, data=full_body)
-    response_json = json.loads(response.content)
+    response_json = json.loads(response.text if hasattr(response, 'text') else response.content)
     
     fileid = response_json.get("id")
-    url = "{}/file/{}/{}".format(file_server_url, uploadid, filename)
+    url = "{}/file/{}/{}".format(fileserver_url, uploadid, dataname)
     
     return {
         "status": response.status_code,
@@ -434,10 +561,10 @@ def plik_oneshot_upload(file_server_url, filename, data):
     }
 
 
-def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_FILESERVER_URL,
+def smartsend(subject, data, broker_url=DEFAULT_BROKER_URL, fileserver_url=DEFAULT_FILESERVER_URL,
               fileserver_upload_handler=plik_oneshot_upload, size_threshold=DEFAULT_SIZE_THRESHOLD,
               correlation_id=None, msg_purpose="chat", sender_name="NATSBridge",
-              receiver_name="", receiver_id="", reply_to="", reply_to_msg_id=""):
+              receiver_name="", receiver_id="", reply_to="", reply_to_msg_id="", is_publish=True):
     """Send data either directly via NATS or via a fileserver URL, depending on payload size.
     
     This function intelligently routes data delivery based on payload size relative to a threshold.
@@ -447,24 +574,38 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
     
     Args:
         subject: NATS subject to publish the message to
-        data: List of (dataname, data, type) tuples to send
+        data: List of (dataname, data, payload_type) tuples to send
-        nats_url: URL of the NATS server
+            - dataname: Name of the payload
+            - data: The actual data to send
+            - payload_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+        broker_url: URL of the NATS server
         fileserver_url: URL of the HTTP file server
-        fileserver_upload_handler: Function to handle fileserver uploads
+        fileserver_upload_handler: Function to handle fileserver uploads (must return dict with "status", "uploadid", "fileid", "url" keys)
-        size_threshold: Threshold in bytes separating direct vs link transport
+        size_threshold: Threshold in bytes separating direct vs link transport (default: 1MB)
-        correlation_id: Optional correlation ID for tracing
+        correlation_id: Optional correlation ID for tracing; if None, a UUID is generated
-        msg_purpose: Purpose of the message
+        msg_purpose: Purpose of the message ("ACK", "NACK", "updateStatus", "shutdown", "chat", etc.)
         sender_name: Name of the sender
-        receiver_name: Name of the receiver
+        receiver_name: Name of the receiver (empty string means broadcast)
-        receiver_id: UUID of the receiver
+        receiver_id: UUID of the receiver (empty string means broadcast)
-        reply_to: Topic to reply to
+        reply_to: Topic to reply to (empty string if no reply expected)
         reply_to_msg_id: Message ID this message is replying to
+        is_publish: Whether to automatically publish the message to NATS (default: True)
+            - When True: message is published to NATS
+            - When False: returns envelope and JSON string without publishing
     
     Returns:
-        MessageEnvelope: The envelope object for tracking
+        tuple: (env, env_json_str) where:
+            - env: MessageEnvelope object with all metadata and payloads
+            - env_json_str: JSON string representation of the envelope for publishing
+    
+    Example:
+        >>> data = [("message", "Hello World!", "text")]
+        >>> env, env_json_str = smartsend("/test", data)
+        >>> # env: MessageEnvelope with all metadata and payloads
+        >>> # env_json_str: JSON string for publishing
     """
     # Generate correlation ID if not provided
-    cid = correlation_id if correlation_id else str(uuid.uuid4())
+    cid = correlation_id if correlation_id is not None else str(uuid.uuid4())
     
     log_trace(cid, "Starting smartsend for subject: {}".format(subject))
     
@@ -479,16 +620,19 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
         payload_bytes = _serialize_data(payload_data, payload_type)
         
         payload_size = len(payload_bytes)
-        log_trace(cid, "Serialized payload '{}' (type: {}) size: {} bytes".format(
+        log_trace(cid, "Serialized payload '{}' (payload_type: {}) size: {} bytes".format(
             dataname, payload_type, payload_size))
         
         # Decision: Direct vs Link
         if payload_size < size_threshold:
             # Direct path - Base64 encode and send via NATS
-            payload_b64 = _serialize_data(payload_bytes, "binary")  # Already bytes
             # Convert to base64 string for JSON
-            import ubinascii
+            try:
-            payload_b64_str = ubinascii.b2a_base64(payload_bytes).decode('utf-8').strip()
+                import ubinascii
+                payload_b64_str = ubinascii.b2a_base64(payload_bytes).decode('utf-8').strip()
+            except ImportError:
+                import base64
+                payload_b64_str = base64.b64encode(payload_bytes).decode('utf-8')
             
             log_trace(cid, "Using direct transport for {} bytes".format(payload_size))
             
@@ -511,10 +655,10 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
             # Upload to HTTP server
             response = fileserver_upload_handler(fileserver_url, dataname, payload_bytes)
             
-            if response["status"] != 200:
+            if response.get("status") != 200:
-                raise Exception("Failed to upload data to fileserver: {}".format(response["status"]))
+                raise Exception("Failed to upload data to fileserver: {}".format(response.get("status")))
             
-            url = response["url"]
+            url = response.get("url")
             log_trace(cid, "Uploaded to URL: {}".format(url))
             
             # Create MessagePayload for link transport
@@ -543,19 +687,21 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
         receiver_id=receiver_id,
         reply_to=reply_to,
         reply_to_msg_id=reply_to_msg_id,
-        broker_url=nats_url,
+        broker_url=broker_url,
         metadata={}
     )
     
     msg_json = env.to_json()
     
-    # Publish to NATS
+    # Publish to NATS if is_publish is True
-    nats_conn = NATSConnection(nats_url)
+    if is_publish:
-    nats_conn.connect()
+        nats_conn = NATSConnection(broker_url)
-    nats_conn.publish(subject, msg_json)
+        nats_conn.connect()
-    nats_conn.close()
+        nats_conn.publish(subject, msg_json)
+        nats_conn.close()
     
-    return env
+    # Return tuple of (envelope, json_string) for both direct and link transport
+    return (env, msg_json)
 
 
 def smartreceive(msg, fileserver_download_handler=_fetch_with_backoff, max_retries=5,
@@ -566,18 +712,29 @@ def smartreceive(msg, fileserver_download_handler=_fetch_with_backoff, max_retri
     (base64 decoded payloads) and link transport (URL-based payloads).
     
     Args:
-        msg: NATS message to process (dict with payload data)
+        msg: NATS message to process (dict or JSON string with envelope data)
         fileserver_download_handler: Function to handle downloading data from file server URLs
-        max_retries: Maximum retry attempts for fetching URL
+            Receives: (url, max_retries, base_delay, max_delay, correlation_id)
-        base_delay: Initial delay for exponential backoff in ms
+            Returns: bytes (the downloaded data)
-        max_delay: Maximum delay for exponential backoff in ms
+        max_retries: Maximum retry attempts for fetching URL (default: 5)
+        base_delay: Initial delay for exponential backoff in ms (default: 100)
+        max_delay: Maximum delay for exponential backoff in ms (default: 5000)
     
     Returns:
-        dict: Envelope dictionary with metadata and 'payloads' field containing list of (dataname, data, type) tuples
+        dict: Envelope dictionary with metadata and 'payloads' field containing list of 
+              (dataname, data, payload_type) tuples
+    
+    Example:
+        >>> env = smartreceive(msg)
+        >>> # env contains envelope metadata and payloads field
+        >>> # env["payloads"] = [(dataname1, data1, payload_type1), ...]
+        >>> for dataname, data, payload_type in env["payloads"]:
+        ...     print("Received {} of type {}: {}".format(dataname, payload_type, data))
     """
     # Parse the JSON envelope
     json_data = msg if isinstance(msg, dict) else json.loads(msg)
-    log_trace(json_data.get("correlationId", ""), "Processing received message")
+    correlation_id = json_data.get("correlation_id", "")
+    log_trace(correlation_id, "Processing received message")
     
     # Process all payloads in the envelope
     payloads_list = []
@@ -591,43 +748,47 @@ def smartreceive(msg, fileserver_download_handler=_fetch_with_backoff, max_retri
         dataname = payload.get("dataname", "")
         
         if transport == "direct":
-            log_trace(json_data.get("correlationId", ""), 
+            log_trace(correlation_id, 
                      "Direct transport - decoding payload '{}'".format(dataname))
             
             # Extract base64 payload from the payload
             payload_b64 = payload.get("data", "")
             
             # Decode Base64 payload
-            import ubinascii
+            try:
-            payload_bytes = ubinascii.a2b_base64(payload_b64.encode('utf-8'))
+                import ubinascii
+                payload_bytes = ubinascii.a2b_base64(payload_b64.encode('utf-8'))
+            except ImportError:
+                import base64
+                payload_bytes = base64.b64decode(payload_b64)
             
             # Deserialize based on type
-            data_type = payload.get("type", "")
+            payload_type = payload.get("payload_type", "")
-            data = _deserialize_data(payload_bytes, data_type, json_data.get("correlationId", ""))
+            data = _deserialize_data(payload_bytes, payload_type, correlation_id)
             
-            payloads_list.append((dataname, data, data_type))
+            payloads_list.append((dataname, data, payload_type))
             
         elif transport == "link":
             # Extract download URL from the payload
             url = payload.get("data", "")
-            log_trace(json_data.get("correlationId", ""),
+            log_trace(correlation_id,
                       "Link transport - fetching '{}' from URL: {}".format(dataname, url))
             
             # Fetch with exponential backoff
             downloaded_data = fileserver_download_handler(
-                url, max_retries, base_delay, max_delay, json_data.get("correlationId", "")
+                url, max_retries, base_delay, max_delay, correlation_id
             )
             
             # Deserialize based on type
-            data_type = payload.get("type", "")
+            payload_type = payload.get("payload_type", "")
-            data = _deserialize_data(downloaded_data, data_type, json_data.get("correlationId", ""))
+            data = _deserialize_data(downloaded_data, payload_type, correlation_id)
             
-            payloads_list.append((dataname, data, data_type))
+            payloads_list.append((dataname, data, payload_type))
             
         else:
             raise ValueError("Unknown transport type for payload '{}': {}".format(dataname, transport))
     
-    # Replace payloads field with the processed list of (dataname, data, type) tuples
+    # Replace payloads field with the processed list of (dataname, data, payload_type) tuples
     json_data["payloads"] = payloads_list
     
     return json_data
@@ -646,11 +807,11 @@ def get_timestamp():
 
 # Example usage
 if __name__ == "__main__":
-    print("NATSBridge for Micropython")
+    print("NATSBridge - Bi-Directional Data Bridge")
-    print("=========================")
+    print("=======================================")
     print("This module provides:")
-    print("  - MessageEnvelope: Message envelope structure")
+    print("  - MessageEnvelope: Message envelope structure with snake_case fields")
-    print("  - MessagePayload: Payload structure")
+    print("  - MessagePayload: Payload structure with payload_type field")
     print("  - smartsend: Send data via NATS with automatic transport selection")
     print("  - smartreceive: Receive and process messages from NATS")
     print("  - plik_oneshot_upload: Upload files to HTTP file server")
@@ -658,10 +819,12 @@ if __name__ == "__main__":
     print()
     print("Usage:")
     print("  from nats_bridge import smartsend, smartreceive")
-    print("  data = [(\"message\", \"Hello World\", \"text\")]")
+    print()
-    print("  env = smartsend(\"my.subject\", data)")
+    print("  # Send data (list of (dataname, data, payload_type) tuples)")
+    print("  data = [(\"message\", \"Hello World!\", \"text\")]")
+    print("  env, env_json_str = smartsend(\"my.subject\", data)")
     print()
     print("  # On receiver:")
-    print("  payloads = smartreceive(msg)")
+    print("  env = smartreceive(msg)")
-    print("  for dataname, data, type in payloads:")
+    print("  for dataname, data, payload_type in env[\"payloads\"]:")
-    print("      print(f\"Received {dataname} of type {type}: {data}\")")
+    print("      print(\"Received {} of type {}: {}\".format(dataname, payload_type, data))")

test/test_js_dict_sender.js

@@ -118,7 +118,7 @@ async function test_dict_send() {
     // Use smartsend with dictionary type
     // For small Dictionary: will use direct transport (JSON encoded)
     // For large Dictionary: will use link transport (uploaded to fileserver)
-    const env = await smartsend(
+    const { env, env_json_str } = await smartsend(
         SUBJECT,
         [data1, data2],
         {
@@ -132,7 +132,8 @@ async function test_dict_send() {
             receiverName: "",
             receiverId: "",
             replyTo: "",
-            replyToMsgId: ""
+            replyToMsgId: "",
+            isPublish: true  // Publish the message to NATS
         }
     );
     

test/test_js_file_sender.js

@@ -98,7 +98,7 @@ async function test_large_binary_send() {
     
     // Use smartsend with binary type - will automatically use link transport
     // if file size exceeds the threshold (1MB by default)
-    const env = await smartsend(
+    const { env, env_json_str } = await smartsend(
         SUBJECT,
         [data1, data2],
         {
@@ -112,7 +112,8 @@ async function test_large_binary_send() {
             receiverName: "",
             receiverId: "",
             replyTo: "",
-            replyToMsgId: ""
+            replyToMsgId: "",
+            isPublish: true  // Publish the message to NATS
         }
     );
     

test/test_js_mix_payload_sender.js

@@ -222,7 +222,7 @@ async function test_mix_send() {
     ];
     
     // Use smartsend with mixed content
-    const env = await smartsend(
+    const { env, env_json_str } = await smartsend(
         SUBJECT,
         payloads,
         {
@@ -236,7 +236,8 @@ async function test_mix_send() {
             receiverName: "",
             receiverId: "",
             replyTo: "",
-            replyToMsgId: ""
+            replyToMsgId: "",
+            isPublish: true  // Publish the message to NATS
         }
     );
     

test/test_js_table_sender.js

@@ -118,7 +118,7 @@ async function test_table_send() {
     // Use smartsend with table type
     // For small Table: will use direct transport (Arrow IPC encoded)
     // For large Table: will use link transport (uploaded to fileserver)
-    const env = await smartsend(
+    const { env, env_json_str } = await smartsend(
         SUBJECT,
         [data1, data2],
         {
@@ -132,7 +132,8 @@ async function test_table_send() {
             receiverName: "",
             receiverId: "",
             replyTo: "",
-            replyToMsgId: ""
+            replyToMsgId: "",
+            isPublish: true  // Publish the message to NATS
         }
     );
     

test/test_js_text_sender.js

@@ -94,7 +94,7 @@ async function test_text_send() {
     // Use smartsend with text type
     // For small text: will use direct transport (Base64 encoded UTF-8)
     // For large text: will use link transport (uploaded to fileserver)
-    const env = await smartsend(
+    const { env, env_json_str } = await smartsend(
         SUBJECT,
         [data1, data2],
         {
@@ -108,7 +108,8 @@ async function test_text_send() {
             receiverName: "",
             receiverId: "",
             replyTo: "",
-            replyToMsgId: ""
+            replyToMsgId: "",
+            isPublish: true  // Publish the message to NATS
         }
     );
     

test/test_julia_dict_sender.jl

@@ -92,12 +92,12 @@ function test_dict_send()
     # Use smartsend with dictionary type
     # For small Dictionary: will use direct transport (JSON encoded)
     # For large Dictionary: will use link transport (uploaded to fileserver)
-    env = NATSBridge.smartsend(
+    env, env_json_str = NATSBridge.smartsend(
         SUBJECT,
         [data1, data2];  # List of (dataname, data, type) tuples
-        nats_url = NATS_URL,
+        broker_url = NATS_URL,
         fileserver_url = FILESERVER_URL,
-        fileserverUploadHandler = plik_upload_handler,
+        fileserver_upload_handler = plik_upload_handler,
         size_threshold = 1_000_000,  # 1MB threshold
         correlation_id = correlation_id,
         msg_purpose = "chat",
@@ -105,7 +105,8 @@ function test_dict_send()
         receiver_name = "",
         receiver_id = "",
         reply_to = "",
-        reply_to_msg_id = ""
+        reply_to_msg_id = "",
+        is_publish = true  # Publish the message to NATS
     )
     
     log_trace("Sent message with $(length(env.payloads)) payloads")
@@ -114,7 +115,7 @@ function test_dict_send()
     for (i, payload) in enumerate(env.payloads)
         log_trace("Payload $i ('$payload.dataname'):")
         log_trace("  Transport: $(payload.transport)")
-        log_trace("  Type: $(payload.type)")
+        log_trace("  Type: $(payload.payload_type)")
         log_trace("  Size: $(payload.size) bytes")
         log_trace("  Encoding: $(payload.encoding)")
         

test/test_julia_file_sender.jl

@@ -79,12 +79,12 @@ function test_large_binary_send()
     # Use smartsend with binary type - will automatically use link transport
     # if file size exceeds the threshold (1MB by default)
     # API: smartsend(subject, [(dataname, data, type), ...]; keywords...)
-    env = NATSBridge.smartsend(
+    env, env_json_str = NATSBridge.smartsend(
         SUBJECT,
         [data1, data2];  # List of (dataname, data, type) tuples
-        nats_url = NATS_URL;
+        broker_url = NATS_URL;
         fileserver_url = FILESERVER_URL,
-        fileserverUploadHandler = plik_upload_handler,
+        fileserver_upload_handler = plik_upload_handler,
         size_threshold = 1_000_000,
         correlation_id = correlation_id,
         msg_purpose = "chat",
@@ -92,11 +92,12 @@ function test_large_binary_send()
         receiver_name = "",
         receiver_id = "",
         reply_to = "",
-        reply_to_msg_id = ""
+        reply_to_msg_id = "",
+        is_publish = true  # Publish the message to NATS
     )
     
     log_trace("Sent message with transport: $(env.payloads[1].transport)")
-    log_trace("Envelope type: $(env.payloads[1].type)")
+    log_trace("Envelope type: $(env.payloads[1].payload_type)")
     
     # Check if link transport was used
     if env.payloads[1].transport == "link"

test/test_julia_mix_payloads_sender.jl

@@ -186,12 +186,12 @@ function test_mix_send()
     ]
     
     # Use smartsend with mixed content
-    env = NATSBridge.smartsend(
+    env, env_json_str = NATSBridge.smartsend(
         SUBJECT,
         payloads;  # List of (dataname, data, type) tuples
-        nats_url = NATS_URL,
+        broker_url = NATS_URL,
         fileserver_url = FILESERVER_URL,
-        fileserverUploadHandler = plik_upload_handler,
+        fileserver_upload_handler = plik_upload_handler,
         size_threshold = 1_000_000,  # 1MB threshold
         correlation_id = correlation_id,
         msg_purpose = "chat",
@@ -199,7 +199,8 @@ function test_mix_send()
         receiver_name = "",
         receiver_id = "",
         reply_to = "",
-        reply_to_msg_id = ""
+        reply_to_msg_id = "",
+        is_publish = true  # Publish the message to NATS
     )
     
     log_trace("Sent message with $(length(env.payloads)) payloads")
@@ -208,7 +209,7 @@ function test_mix_send()
     for (i, payload) in enumerate(env.payloads)
         log_trace("Payload $i ('$payload.dataname'):")
         log_trace("  Transport: $(payload.transport)")
-        log_trace("  Type: $(payload.type)")
+        log_trace("  Type: $(payload.payload_type)")
         log_trace("  Size: $(payload.size) bytes")
         log_trace("  Encoding: $(payload.encoding)")
         

test/test_julia_table_sender.jl

@@ -90,12 +90,12 @@ function test_table_send()
     # Use smartsend with table type
     # For small DataFrame: will use direct transport (Base64 encoded Arrow IPC)
     # For large DataFrame: will use link transport (uploaded to fileserver)
-    env = NATSBridge.smartsend(
+    env, env_json_str = NATSBridge.smartsend(
         SUBJECT,
         [data1, data2];  # List of (dataname, data, type) tuples
-        nats_url = NATS_URL,
+        broker_url = NATS_URL,
         fileserver_url = FILESERVER_URL,
-        fileserverUploadHandler = plik_upload_handler,
+        fileserver_upload_handler = plik_upload_handler,
         size_threshold = 1_000_000,  # 1MB threshold
         correlation_id = correlation_id,
         msg_purpose = "chat",
@@ -103,7 +103,8 @@ function test_table_send()
         receiver_name = "",
         receiver_id = "",
         reply_to = "",
-        reply_to_msg_id = ""
+        reply_to_msg_id = "",
+        is_publish = true  # Publish the message to NATS
     )
     
     log_trace("Sent message with $(length(env.payloads)) payloads")
@@ -112,7 +113,7 @@ function test_table_send()
     for (i, payload) in enumerate(env.payloads)
         log_trace("Payload $i ('$payload.dataname'):")
         log_trace("  Transport: $(payload.transport)")
-        log_trace("  Type: $(payload.type)")
+        log_trace("  Type: $(payload.payload_type)")
         log_trace("  Size: $(payload.size) bytes")
         log_trace("  Encoding: $(payload.encoding)")
         

test/test_julia_text_sender.jl

@@ -75,12 +75,12 @@ function test_text_send()
     # Use smartsend with text type
     # For small text: will use direct transport (Base64 encoded UTF-8)
     # For large text: will use link transport (uploaded to fileserver)
-    env = NATSBridge.smartsend(
+    env, env_json_str = NATSBridge.smartsend(
         SUBJECT,
         [data1, data2];  # List of (dataname, data, type) tuples
-        nats_url = NATS_URL,
+        broker_url = NATS_URL,
         fileserver_url = FILESERVER_URL,
-        fileserverUploadHandler = plik_upload_handler,
+        fileserver_upload_handler = plik_upload_handler,
         size_threshold = 1_000_000,  # 1MB threshold
         correlation_id = correlation_id,
         msg_purpose = "chat",
@@ -88,7 +88,8 @@ function test_text_send()
         receiver_name = "",
         receiver_id = "",
         reply_to = "",
-        reply_to_msg_id = ""
+        reply_to_msg_id = "",
+        is_publish = true  # Publish the message to NATS
     )
     
     log_trace("Sent message with $(length(env.payloads)) payloads")
@@ -97,7 +98,7 @@ function test_text_send()
     for (i, payload) in enumerate(env.payloads)
         log_trace("Payload $i ('$payload.dataname'):")
         log_trace("  Transport: $(payload.transport)")
-        log_trace("  Type: $(payload.type)")
+        log_trace("  Type: $(payload.payload_type)")
         log_trace("  Size: $(payload.size) bytes")
         log_trace("  Encoding: $(payload.encoding)")
         

test/test_micropython_dict_sender.py

@@ -64,7 +64,7 @@ def main():
     log_trace(correlation_id, f"Correlation ID: {correlation_id}")
     
     # Use smartsend with dictionary type
-    env = smartsend(
+    env, env_json_str = smartsend(
         SUBJECT,
         [data1, data2],  # List of (dataname, data, type) tuples
         nats_url=NATS_URL,
@@ -76,7 +76,8 @@ def main():
         receiver_name="",
         receiver_id="",
         reply_to="",
-        reply_to_msg_id=""
+        reply_to_msg_id="",
+        is_publish=True  # Publish the message to NATS
     )
     
     log_trace(correlation_id, f"Sent message with {len(env.payloads)} payloads")

test/test_micropython_file_sender.py

@@ -44,7 +44,7 @@ def main():
     log_trace(correlation_id, f"Correlation ID: {correlation_id}")
     
     # Use smartsend with binary type
-    env = smartsend(
+    env, env_json_str = smartsend(
         SUBJECT,
         [data1, data2],  # List of (dataname, data, type) tuples
         nats_url=NATS_URL,
@@ -56,7 +56,8 @@ def main():
         receiver_name="",
         receiver_id="",
         reply_to="",
-        reply_to_msg_id=""
+        reply_to_msg_id="",
+        is_publish=True  # Publish the message to NATS
     )
     
     log_trace(correlation_id, f"Sent message with {len(env.payloads)} payloads")

test/test_micropython_mixed_sender.py

@@ -58,7 +58,7 @@ def main():
     log_trace(correlation_id, f"Correlation ID: {correlation_id}")
     
     # Use smartsend with mixed types
-    env = smartsend(
+    env, env_json_str = smartsend(
         SUBJECT,
         data,  # List of (dataname, data, type) tuples
         nats_url=NATS_URL,
@@ -70,7 +70,8 @@ def main():
         receiver_name="",
         receiver_id="",
         reply_to="",
-        reply_to_msg_id=""
+        reply_to_msg_id="",
+        is_publish=True  # Publish the message to NATS
     )
     
     log_trace(correlation_id, f"Sent message with {len(env.payloads)} payloads")

test/test_micropython_text_sender.py

@@ -46,7 +46,7 @@ def main():
     # Use smartsend with text type
     # For small text: will use direct transport (Base64 encoded UTF-8)
     # For large text: will use link transport (uploaded to fileserver)
-    env = smartsend(
+    env, env_json_str = smartsend(
         SUBJECT,
         [data1, data2],  # List of (dataname, data, type) tuples
         nats_url=NATS_URL,
@@ -58,7 +58,8 @@ def main():
         receiver_name="",
         receiver_id="",
         reply_to="",
-        reply_to_msg_id=""
+        reply_to_msg_id="",
+        is_publish=True  # Publish the message to NATS
     )
     
     log_trace(correlation_id, f"Sent message with {len(env.payloads)} payloads")